brave new world two days for 2005

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Copyright 2000-2005 Steven Feuerstein - Page 1

The Brave New Worldof Oracle PL/SQL

"Gotta Know, Gotta Use"New Features of

Oracle8i, Oracle9i and Oracle10g PL/SQL

Steven [email protected]

m

All non-technical views expressed are those of Steven Feuerstein and donot necessarily (and not likely!) reflect those of Quest or the TCOUG.


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The New Topography of a PowerfulLanguage

New/enhanced data structures and data types Collections, object types, TIMESTAMP,

INTERVAL, XMLType

Enhancements to the SQL-PL/SQL interface Native Dynamic SQL, bulk processing, record-

based DML

Miscellaneous - but not leftovers

DBMS_UTILITY.FORMAT_ERROR_BACKTRACE, Javafrom PL/SQL, UTL_FILE enhancements, CASE,row level security


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"All" about Steven Feuerstein

Bachelor's degree in mathematics (1980), with threecomputer 101 classes to my name (a self-taughtprogrammer).

Five years with Oracle Corporation (1987 - 1992), withtoo much time spent helping salespeople sell. Life istoo short...

Author/co-author of nine texts on PL/SQL, most

notably Oracle PL/SQL Programming. I live in Chicago with one wife (Veva), two sons (Chris

and Eli), and three cats (Sister, Moshe and Mica).

www.stevenfeuerstein.co


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Ten Years of Writing onthe Oracle PL/SQL Language


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Software Used in Training

You can download all my training materials anddemonstration scripts from:

http://oracleplsqlprogramming.com/resources.html

Toad and/or SQL Navigator: make sure you've got a top-notch IDE, otherwise you are wasting lots of time.

Ounit and utPLSQL, software for unit testing of PL/SQL codeat www.ounit.com.

Mastoid Mind and Set: have fun while keepingyour brain tuned up.

Qnxo, active mentoring software: a repository ofreusable and templated code, www.qnxo.com.plsql_ides.txt


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About Qnxo

Qnxo is a searchable, customizable repository forreusable code and templates.

Starter set: "PL/SQL by Feuerstein"

You can create our own toolboxes and libraries.

Qnxo is a flexible code generator that helps youavoid writing tedious, repetitive code.

Qnxo is an error manager for PL/SQL-basedapplications.


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Qnxo is....

NOT an integrated development environment,aka IDE, aka editor, for PL/SQL programming. It complements Toad, SQL Navigator, PL/SQL

Developer, etc.

NOT free. Qnxo is sold on a subscription basis (youare paying for content).There is a trial version and there will be a free

version in the future (design platform minus

content). NOT neededin order to benefit from this class.

Qnxo contains a repository of examples.

The Qnxo backend reflects my latest (and, I

But we will raffle off a one year sub in class!


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Some PL/SQL Fundamentals

The STANDARD package and how to be aPL/SQL sleuth

The PL/SQL run-time memory architecture

Quick reminders about packages Overloading: use it to improve the usability

of your code.

Packaged data

The initialization section

Packages or stand-alone programs?


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The STANDARD Package and theRdbms/Admin Directory

Much of what we consider to be the basePL/SQL language is defined in the STANDARDpackage.

One of two "default" packages; the other isDBMS_STANDARD.

You can view the contents of the STANDARDpackage (and other "supplied" packages by

visiting the appropriate variation of:$ORACLE_HOME/Rdbms/Admin


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System Global Area (SGA) of RDBMS

Instance

PL/SQL in Shared Memory

Shared Pool

Large Pool

Reserved Pool

show_empscalc_totals upd_salaries

Select *from emp

Shared SQL

Pre-parsedUpdate empSet sal=...

Library cache

Session 1 memory(PGA/UGA)

emp_rec emp%rowtype;tot_tab tottabtype;

Session 2 memory(PGA/UGA)

emp_rec emp%rowtype;tot_tab tottabtype;Session 1

Session 2

mysess.pkgSess2.sql


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Code and Data in Shared Memory

PL/SQL is an interpretative language. The sourcecode is partially compiled into an intermediate form(p-code). The p-code is loaded into the shared pool when any

element of that code (package or stand-alone

program) is referenced. The partially-compiled code is shared among all

users who have EXECUTE authority on theprogram/package.

Each user (Oracle session) has its own copy of anydata structures defined within the program/package. Distinct sets of in-memory data (not shared among

different users) are stored in the PGA.


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Overloading in packages:key usability technique

Overloading: two or more programs with thesame name, but different signature.You can overload in the declaration section

of any PL/SQL block, including the package

body (most common). Overloading is a critical feature when building

comprehensive programmatic interfaces(APIs) or components using packages.

If you want others to use your code, youneed to make that code as smart and aseasy to use as possible.

Overloading transfers the "need to know"from the user to the overloaded ro ram.

myproc

myfunc

myproc

Compare: DBMS_OUTPUT and p


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How Overloading Works

For two or more modules to be overloaded,the compiler must be able to distinguishbetween the two calls at compile-time. Another name for overloading is "static

polymorphism."

There are two different "compile times":

1. When you compile the package or block

containing the overloaded code. 2. When you compile programs that use

the overloaded code.


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How Overloading Works, continued

Distinguishing characteristics:The formal parameters of overloaded modules

must differ in number, order or datatype family(CHAR vs. VARCHAR2 is not different enough).

The programs are of different types: procedureand function.

Undistinguishing characteristics: Functions differ only in their RETURN datatype.

Arguments differ only in their mode (IN, OUT, INOUT).

Their formal parameters differ only in datatypeand the datatypes are in the same family.


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Examples of Invalid Overloadings

PACKAGE too_similar

IS PROCEDURE calc (reg_in IN CHAR);PROCEDURE calc (reg_in IN VARCHAR2);

END too_many_cals;

PACKAGE only_returns

IS FUNCTION func1 (val IN VARCHAR2) RETURN DATE;FUNCTION func1 (val IN VARCHAR2) RETURN VARCHAR2;

END only_returns;

PACKAGE param_modes

ISPROCEDURE proc1 (val IN VARCHAR2);PROCEDURE proc1 (val IN OUT VARCHAR2);

END param_modes;

Parameter

data typescause conflict.

Only differenceis function

RETURN type.

Only differenceis parameter

mode.

too_similar.calc ('123');which one?

DBMS_OUTPUT.PUT_LINE (only_returns.func1 (v_value));which one?

param_modes.proc1 (v_value);which one?


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Quiz! Nuances of Overloading

Is this a valid overloading? Will it compile? Howcan I use it?

CREATE OR REPLACE PACKAGE salesIS

PROCEDURE calc_total (zone_in IN VARCHAR2);

PROCEDURE calc_total (reg_in IN VARCHAR2);END sales;

BEGINsales.calc_total ('NORTHWEST');

sales.calc_total ('ZONE2');END;

sales.pkg

?


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Package Data: Useful and Sticky

The scope of a package is your session, and anydata defined at the "package level" also hassession scope. If defined in the package specification, any

program can directly read/write the data.

Ideal for program-specific caching. General best practice: hide your package data in

the body so that you can control access to it. Use the SERIALLY_REUSABLE pragma to move

data to SGA and have memory released after eachusage.

thisuser.pkgthisuser.tstserial.sql


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Package Initialization Structure

The initialization section:

Is defined after and outsideof any programs in thepackage.

Is not required. In fact, mostpackages you build won't

have one. Can have its own exception

handling section.

Useful for:

Performing complex settingof default or initial values.

Setting up package datawhich does not change forthe duration of a session.

PACKAGE BODY pkgIS

PROCEDURE proc ISBEGINEND;

FUNCTION func RETURNBEGINEND;

BEGIN...initialize...

END pkg;

BEGIN after/outsideof any program

defined in the pkg.init.pkginit.tst

datemgr.pkg


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Packages vs. Stand-alone programs

General recommendation: use packagesinstead of stand-alone programs.

Better way to organize code.

Can hide implementation and reduce needto recompile programs using the package.

Other considerations....

Entire package loaded when any single

program is called. Central packages can become a

"bottleneck" when changes are needed.recompile.sql


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PL/SQL Collections

Collections are single-dimensionedlistsof information, similar to 3GL arrays.

They are an invaluable data structure; allPL/SQL developers should be familiarwith them -- and use them a lot.

They take some getting used to,especially when you want to leverage the

latest features, such as multi-levelcollections.

array (15) array (15, 77)


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Why Use Collections?

Maintain any kind of list of related information for usein your programs.

Emulate bi-directional cursors, which are not yet

supported in PL/SQL Cache data in program memory for faster access. Avoid mutating table errors in database triggers. Mirror complex data structures from database

directly in program data structures. Emulate multi-dimensional arrays in PL/SQL.


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Three Types of Collections

Associative arrays - previously known as "index-bytables" (V8) and "PL/SQL tables" (V7) Available in PL/SQL only; preferred structures for

developers as they are the easiest to use.

Nested tables

Can be defined in PL/SQL and SQL. Use to store largeamounts of persistent data in the column of a table, usewith table functions.

Required for some features, such as table functions

Variable arrays Can be defined in PL/SQL and SQL; useful for definingsmall lists in columns of relational tables.

assoc_array_example.sqnested_table_example.sq

varray_example.sql


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Getting to Know Collections

Defining collection types and collections Navigating collection contents

Manipulating collections inside SQL

New features in Oracle9i Multi-level collections

Indexing by strings

New features in Oracle10g Nested table operators


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Defining Collections

First, you define the TYPE of the collection. For associative arrays, this can only occur in a PL/SQL

declaration section. Best option: package specification.

For nested tables and VARRAYs, you can define the TYPEin the database with a CREATE statement, or in a PL/SQLdeclaration section.

Then you declare one or more instances, actualcollections, from the TYPE..

CREATE OR REPLACE PACKAGE coll_typesIS

TYPE integer_aat IS TABLE OF INTEGER INDEX BY PLS_INTEGER;TYPE integer_nt IS TABLE OF INTEGER;TYPE integer_vat IS VARRAY(10) OF INTEGER;...

END coll_types;


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Initializing Collections

Before you can use a collection, it must be initialized. Nested tables and VARRAYs are atomically null. You must

initialize them explicitly with a constructor. Associative arraysare initialized automatically.

DECLARETYPE numbers_t IS VARRAY (10) OF NUMBER;

salaries numbers_t := numbers_t (100, 200, 300);BEGIN

CREATE TYPE numbers_t IS VARRAY (10) OF NUMBER;/DECLARE -- Initialize the collection.

salaries numbers_t := numbers_t (100, 200, 300);

BEGIN

TYPE defined inthe database

TYPE defined in

PL/SQL

CREATE TABLE employee_denorm (employee_id INTEGER,salary_history numbers_t);

Collection usedin a table

b i i


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More about Associative Arrays

They are unbounded, practically speaking. Valid row numbers range: -2,147,483,647 to2,147,483,647. You will not actually create tables thislarge; they will use up all available memory.

Instead, this range allows you to employ the row number

as an intelligent key, such as the primary key or uniqueindex value, because AAs are:

Sparse Data does not have to be stored in consecutive rows, as

is required in traditional 3GL arrays. Try to read a row that doesn't exist and Oracle

raises NO_DATA_FOUND. emplu.*


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Wide Variety of Collection Methods

Obtain information about the collection

COUNT returns number of rows currently defined incollection.

EXISTS returns TRUE if the specified row is defined.

FIRST/LAST return lowest/highest numbers of defined rows.

NEXT/PRIOR return the closest defined row after/before thespecified row.

LIMIT tells you the max. number of elements allowed in aVARRAY.

Modify the contents of the collection

DELETE deletes one or more rows from the index-by table. EXTEND adds rows to a nested table or VARRAY.

TRIM removes rows from a VARRAY.

Th DELETE M th d


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The DELETE Method

You can delete one or more rows from a collectionusing DELETE:

BEGIN-- Delete all rows

myCollection.DELETE;

-- Delete one (the last) rowmyCollection.DELETE (myCollection.LAST);

-- Delete a range of rows

myCollection.DELETE (1400, 17255);END;

DELETE releases memory, but you may also want to callDBMS_SESSION.FREE_UNUSED_USER_MEMORY.

h h C ll


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Navigating Through Collections

Use FIRST and NEXT to move from beginning to end. Use LAST and PRIOR to move from end to beginning.

rowind PLS_INTEGER := birthdays.FIRST;-- REVERSE: birthdays.LAST

BEGINWHILE (rowind IS NOT NULL)LOOP

DBMS_OUTPUT.PUT_LINE (birthdays(rowind).best_present);

rowind := birthdays.NEXT (rowind);-- REVERSE: birthdays.PRIOR

END LOOP;END;

plsqlloops.spnotworking.sql

notworking_NT.sqlnotworking_VA.sql

U i C ll ti I id SQL


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Using Collections Inside SQL

You can apply SQL operations to the contents ofnested tables and VARRAYs with these operators: CAST - Maps a collection of one type to a collection

of another type

MULTISET - Maps a database table to a collection

TABLE - Maps a collection to a database table

Index-by tables are programmatic constructs only. You cannot make a direct reference to an index-by

table in SQL.

Instead, do so indirectly with a PL/SQL function.

Using Collections inside SQL


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Using Collections inside SQL

Lisa MarieGary Richard

BOND

BOLZ

Barbara Annedb_family

surname children

Max RichardEric Thomas

Lisa MarieGary RichardBarbara Annecolumn_value

SELECT column_valueFROM TABLE (SELECT children FROM db_family

WHERE surname = 'BOLZ');

UPDATE TABLE(SELECT children FROM db_family

WHERE SURNAME = 'BOLZ)SET column_value = 'Lisa Nadezhka' WHERE column_value = 'Lisa Marie');

Lisa NadezhkaGary RichardBarbara Anne

. . .

BOLZ

db_family

surname children

Using the TABLE and CAST Operators


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Using the TABLE and CAST Operators

Use CAST to convert a collection from one type to another,

TABLE to convert a TYPE into a database table. Useful when you would like to apply SQL operations against

a PL/SQL collection (ie, one not stored in a database table).

DECLAREnyc_devolution cutbacks_for_taxcuts :=

cutbacks_for_taxcuts ('Stop rat extermination programs','Fire building inspectors','Close public hospitals');

BEGINDBMS_OUTPUT.PUT_LINE (

'How to Make the NYC Rich Much, Much Richer:');FOR rec IN (SELECT COLUMN_VALUE ohmy

FROMTABLE (CAST (nyc_devolutionAS cutbacks_for_taxcuts)))LOOP

DBMS_OUTPUT.PUT_LINE (rec.ohmy);END LOOP;

END;cast.sql

Using the MULTISET Operator


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Using the MULTISET Operator

MULTISET is the inverse of TABLE, converting a set oftable, view, query) into a VARRAY or nested table. Use MULTISET to emulate or transform relational joins into

collections, with potential client-server performance impact.

DECLARECURSOR bird_curs IS

SELECT b.genus, b.species,CAST(MULTISET(SELECT bh.country FROM bird_habitats bh

WHERE bh.genus = b.genusAND bh.species = b.species)

AS country_tab_t)FROM birds b;

bird_row bird_curs%ROWTYPE;BEGIN

OPEN bird_curs;FETCH bird_curs into bird_row;

END;multiset.sql

Retrieves all detail

information for themaster in one trip.

Referencing Associative Arrays inside SQL


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CREATE OR REPLACE PACKAGE ibtab ISFUNCTION rowval (indx IN PLS_INTEGER) RETURN DATE;PRAGMA RESTRICT_REFERENCES (rowval, WNPS, WNDS);

END;

CREATE OR REPLACE PACKAGE BODY ibtab ISTYPE date_tab IS TABLE OF DATE INDEX BY BINARY_INTEGER;hiredates date_tab;

FUNCTION rowval (indx IN PLS_INTEGER) RETURN DATEIS BEGIN

RETURN hiredates (indx);END;

END;

Referencing Associative Arrays inside SQL

You can't directly reference an index-by table'scontents inside SQL. Call functions that retrieve data from hidden array.

ibtab_in_sql.sql

Make accessiblein SQL forOracle8 and

below.

Putting Collections to Work


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Putting Collections to Work

Let's take a closer look at some of the waysyou can use collections in PL/SQL programs.

Enhancing date-string conversion Bi-directional cursor emulation

Data caching

Mutating table error resolution

datemgr*.pkgdates.sql

bidir.*emplu.*

The Mutating Table Problem


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The Mutating Table Problem

Row level triggers cannot query from orchange the contents of the table to which itis attached; it is "mutating".

So what are you supposed to do when arow-level operation needs to "touch" thattable?

UPDATE row 1

UPDATE row N

UPDATE emp SET sal = 1000

Database triggers can be associated with both the

DML statement as a whole and individual rowsaffected by that statement.

Note: in Oracle8i, youcan use autonomoustransactions to relax

restrictionsassociated with

queries.

mutating.sql

Statement level

Row level

A Solution Based on


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Associative Arrays Tables

Since you cannot perform the processing desiredin the row-level trigger, you need to defertheaction until you get to the statement level.

If you are going to defer the work, you have toremember what you needed to do. an index-by table is an ideal repository for this

reminder list.

1st row trigger fires

Nth row trigger fires

Work List(PL/SQL Table)

Statement Trigger

Writes to list

Writes to list

Process datain the list.

An Example:R ki S l l


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Ranking Salespeople

A table holds the rankings based on the amount of annual sales

of salespeople within a department. As the sales amount is updated in this table, the rankingsmust also change to show the new standings for thatdepartmentonly.

Salesperson ID Sales Amount RankDepartment ID

1055 64333 74055.88 3

1055 65709 144533.91

1055 65706 109000.25

1047 70904 65011.25

1

2

6

"Deferred work" is not only necessary, but preferable.

By storing the salespersons department ids as theychange, we then know which departments to re-rank.

We might update more than one department within astatement so we must be able to retain multipledepartment numbers.

T i L i R i d


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Trigger Logic Required

CREATE OR REPLACE TRIGGER Rank_Sales_StrgAFTER INSERT OR UPDATE OR DELETEON rank_sales

BEGIN rank.rank_depts;END;

Statement Level Trigger

All details of theranking are hidden

in the package body.

CREATE OR REPLACE TRIGGER Rank_Sales_RtrgAFTER insert OR update OF sales_amtON rank_sales FOR EACH ROW

WHEN (OLD.sales_amt != NEW.sales_amt)BEGIN rank.add_dept (:new.dept_id);

END;

Row Level Trigger

Doesn't fire unlessthe sales_amtis actually changed.

ranking.pkg

The Ranking Package


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The Ranking Package

PACKAGE rankIS

PROCEDURE add_dept (dept_id_in IN INTEGER);

PROCEDURE rank_depts;END rank;

PACKAGE BODY rankISin_process BOOLEAN := FALSE;

TYPE dept_tabtype IS TABLE OF BOOLEAN INDEX BY BINARY_INTEGER;dept_tab dept_tabtype;

PROCEDURE add_dept (dept_id_in IN INTEGER) ISBEGINIF NOT in_process

THENdept_tab (dept_id_in) := TRUE;

END IF;END add_dept

Table holds indicatorthat department

needs re-ranking.

Create row to indicatedepartment to be ranked.

The Ranking Package Continued


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The Ranking Package, Continued

PROCEDURE rank_depts

ISv_deptid PLS_INTEGER := dept_tab.FIRST;BEGIN

IF NOT in_processTHENin_process := TRUE;LOOPEXIT WHEN v_deptid IS NULL;

perform_ranking (v_deptid);v_deptid := dept_tab.NEXT (v_deptid);

END LOOP;END IF;

in_process := FALSE;

dept_tab.DELETE;END rank_dept;

END rank;

Avoid recursiveexecution of logic

Row number isdepartment number.

Clean up fornext time.

Multi-level CollectionsOracle9i


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Multi level Collections

Oracle9i allows you to create collections ofcollections, or collections of records thatcontain collections, or...

Applies to all three types of collections.

Two scenarios to be aware of:

Named collection columns

Anonymous collection columns

Collections with Named,M lti l l C ll ti

Oracle9i


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Multi-level Collections

When a collection is based on a record orobject that in turn contains a collection, thatcollection has a name.

CREATE TYPE vet_visit_t IS OBJECT (visit_date DATE,reason VARCHAR2 (100));

/CREATE TYPE vet_visits_t IS TABLE OF vet_visit_t/CREATE TYPE pet_t IS OBJECT (

tag_no INTEGER,NAME VARCHAR2 (60),

petcare vet_visits_t,MEMBER FUNCTION set_tag_no (new_tag_no IN INTEGER)

RETURN pet_t);/

Continued...multilevel_collections.sql

Collection nested insideobject type

Collections with Named,M lti l l C ll ti ti d

Oracle9i


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Multi-level Collections, continued

DECLARETYPE bunch_of_pets_t IS TABLE OF pet_t INDEX BY BINARY_INTEGER;my_pets bunch_of_pets_t;

BEGINmy_pets (1) :=

pet_t (

100, 'Mercury',vet_visits_t (

vet_visit_t ('01-Jan-2001', 'Clip wings'),

vet_visit_t ('01-Apr-2002', 'Check cholesterol')

)

);DBMS_OUTPUT.put_line (my_pets (1).petcare (2).reason);END;

Outer collection

Inner collection

Anonymous Collection ColumnsOracle9i


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y

If your nested collections do not rely on "intermediate"

records or objects, you simply string together indexsubscripts. To demonstrate this syntax, let's take a look at how to

emulate a three-dimensional array using nestedcollections.

First, we cannot directly reference or populate anindividual cell, as one would do in a 3GL. Instead we have to build an interface between the

underlying arrays and the user of the "three

dimensional array."BEGINgps_info (1, 45, 605) :=

l_value;

BEGINgps_info (605) (45) (1) :=

l_value;

Can't do this... Have to do something like this instead...

Multi-dimensional array emulation

Oracle9i


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y

CREATEORREPLACEPACKAGE multdimIS TYPE dim1_t ISTABLEOFVARCHAR2(32767)

INDEXBYBINARY_INTEGER;

TYPE dim2_t ISTABLEOF dim1_t INDEXBYBINARY_INTEGER;

TYPE dim3_t ISTABLEOF dim2_t INDEXBYBINARY_INTEGER;

PROCEDURE setcell (array_in INOUT dim3_t,dim1_in PLS_INTEGER,dim2_in PLS_INTEGER,dim3_in PLS_INTEGER,value_in IN VARCHAR2

);

FUNCTION getcell (

array_in IN dim3_t,dim1_in PLS_INTEGER,dim2_in PLS_INTEGER,dim3_in PLS_INTEGER

) RETURN VARCHAR2;END multdim;

multdim.*multdim2.*

gen_multcoll.sp

Three levels ofcollections

Set a cell value

Get a cell value

Multi-dimensional array emulation

Oracle9i


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y

CREATEORREPLACEPACKAGEBODYmultdimIS PROCEDURE setcell (

array_in INOUT dim3_t,dim1_in PLS_INTEGER,dim2_in PLS_INTEGER,dim3_in PLS_INTEGER,value_in IN VARCHAR2

)IS BEGIN

array_in(dim3_in )(dim2_in )(dim1_in):= value_in; END;

FUNCTION getcell (array_in IN dim3_t,dim1_in PLS_INTEGER,dim2_in PLS_INTEGER,dim3_in PLS_INTEGER)

RETURNVARCHAR2 IS BEGIN RETURN array_in(dim3_in )(dim2_in )(dim1_in);

END;

multdim.*multdim2.*

gen_multcoll.sp

As close as youcan get...


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Examples of NewTYPE Variants

Oracle9iRelease 2


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TYPE Variants

All of the following are now valid TYPE declarations inOracle9i Release 2 You cannot use %TYPE against an INTEGER column,

because INTEGER is nota subtype of BINARY_INTEGER.

DECLARETYPE array_t1 IS TABLE OF NUMBER INDEX BY BINARY_INTEGER;TYPE array_t2 IS TABLE OF NUMBER INDEX BY PLS_INTEGER;TYPE array_t3 IS TABLE OF NUMBER INDEX BY POSITIVE;TYPE array_t4 IS TABLE OF NUMBER INDEX BY NATURAL;TYPE array_t5 IS TABLE OF NUMBER INDEX BY VARCHAR2(64);TYPE array_t6 IS TABLE OF NUMBER INDEX BY VARCHAR2(32767);

TYPE array_t7 IS TABLE OF NUMBER INDEX BYemployee.last_name%TYPE;TYPE array_t8 IS TABLE OF NUMBER INDEX BY

types_pkg.subtype_t;

Working with VARCHAR2-IndexedCollections

Oracle9iRelease 2


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Collections

Specifying a row via a string takes some gettingused to, but if offers some very powerful advantages.

DECLARE

TYPE population_type IS TABLE OF NUMBER INDEX BY VARCHAR2(64);

country_population population_type;continent_population population_type;

howmany NUMBER;BEGIN

country_population('Greenland') := 100000;country_population('Iceland') := 750000;

howmany := country_population('Greenland');

continent_population('Australia') := 30000000;END;

assoc_array*.sqlassoc_array_perf.tst

Rapid Access to DataVia String Keys

Oracle9iRelease 2


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Via String Keys

One of the most powerful applications of this

features is to construct very fast pathways to staticdata from within PL/SQL programs. If you are repeatedly querying the same data from the

database, why not cache it in your PGA inside

collections? Emulate the various indexing mechanisms (primary

key, unique indexes) with collections.

Demonstration package:assoc_array5.sql

Comparison of performanceof different approaches:

vocab*.*

Generate a caching package:genaa.sql

The power of multi-level and string-based indexes


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based indexes

Careful -- and creative! -- application of thisfunctionality can greatly simplify the code you need towrite to handle complex requirements.

Let's step through a demonstration of this capabilityusing Codecheck as an example.

overloadings

naming_conventionsbad_datatypes

CodecheckpackageCodecheck:

A QA package

for PL/SQL

The problem ofambiguous package overloadings


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ambiguous package overloadings

Oddly and sadly, it is possible to compileoverloadings which are not usable.You see an obvious example below, but there are

many more subtle circumstances, usuallyinvolving defaulted parameters.

So I will build a program to identify such ambiguousoverloadings. But how can I do this?

BEGINsalespkg.calc_total ('ABC');

END;/

PACKAGE salespkgIS

PROCEDURE calc_total (dept_in IN VARCHAR2);

PROCEDURE calc_total (dept_in IN CHAR);

END salespkg; ?

ALL_ARGUMENTS to the rescue!


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Parsing is too complicated for me, but theALL_ARGUMENTS data dictionary viewcontains information about all the argumentsof all the procedures and functions to which Ihave access. That sounds pretty good!

As usual, Oracle offers us a whole lot ofpleasure, mixed with a little bit of pain.The organization of data in

ALL_ARGUMENTS is a bit bizarre, plus it isincomplete, necessitating the use also ofDBMS_DESCRIBE.DESCRIBE_COLUMNS.

First Inclination:Same Old, Same Old


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Same Old, Same Old

All right then, I will grab all the information from

ALL_ARGUMENTS and dump it into a collectionbased on that view! Very easy...

CREATE OR REPLACE PROCEDURE get_all_arguments (package_in IN VARCHAR2)

ISTYPE all_arguments_tt IS TABLE OF all_arguments%ROWTYPE

INDEX BY BINARY_INTEGER;l_arguments all_arguments_tt;

BEGINFOR rec IN (SELECT * FROM all_argumentsWHERE owner = USER AND package_name = package_in)

LOOPl_arguments (SQL%ROWCOUNT) := rec;

END LOOP;END;

Load it up!

Emulate theview.

Then what? Write lots of code tointerpret the contents...


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interpret the contents...

Which programs are overloaded? Wheredoes one overloading end and another start?

l_last_program all_arguments.object_name%TYPE;l_is_new_program BOOLEAN :=FALSE;l_last_overload PLS_INTEGER :=-1;

BEGIN

FORindx IN l_arguments.FIRST ..l_arguments.LAST

LOOP IF l_arguments (indx).object_name !=

l_last_program ORl_last_programISNULL THEN

l_last_program:=

l_arguments (indx).object_name;l_is_new_program:=TRUE;do_new_program_stuff;

ENDIF;...

IF l_arguments (indx).overload!= l_last_overload

ORl_last_overload=-1 THEN IF l_is_new_program THEN

do_first_overloading_stuff; ELSE

do_new_overloading_stuff; ENDIF;

ENDIF; ENDLOOP;END;

Discovery: there is a natural hierarchyto ALL ARGUMENTS data!


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to ALL_ARGUMENTS data!

Each program has zero ormore overloadings, eachoverloading has Narguments, and eachargument can havemultiple "breakouts" (my

term - applies to non-scalar parameters, such asrecords or object types).

RUN_TEST

SHOW_RESULTS

RESET_FLAGS

Program name

Overloading 1

Overloading 2

Overloading

Argument 1

Argument 2

Argument 3

Argument 4

Argument 5

ArgumentBreakout 1

Breakout 1

Breakout 2

Breakout 3

Breakout

What if I reflect this hierarchy ina collection of collections?


59/280


Have to build from the bottom up:TYPE breakouts_t IS TABLE OF all_arguments%ROWTYPE

INDEX BY BINARY_INTEGER;

TYPE arguments_t IS TABLE OF breakouts_t

INDEX BY BINARY_INTEGER;

TYPE overloadings_t IS TABLE OF arguments_tINDEX BY BINARY_INTEGER;

TYPE programs_t IS TABLE OF overloadings_tINDEX BY all_arguments.object_name%type;

1. Set of rows fromALL_ARGUMENTS

String-based index

2. All the "breakout" info

for a single argument

3. All the argument infofor a single overloading

4. All the overloadings fora distinct program name

Then I can populate it very easily


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Assigning a single record to the "lowest" level alsodefines each of the upper levels. Notice the automatic "SELECT DISTINCT" on program

name that results!

FOR rec IN (SELECT * FROM all_arguments)LOOPl_arguments (NVL (l_arguments.LAST,0)+1)

:= rec;

l_programs (rec.object_name) (NVL (rec.overload,0)) (rec.position) (rec.data_level):= rec;ENDLOOP;

I can still do thetypical sequential

load.

But I will now also

add the multi-levelload in singleassignment

A closer look at the multi-levelassignment


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g

g_programs(c_program)

(c_overload).PARAMETERS

(c_position).toplevel

all programs in packagedistinct program name in package

Nth overloading for program (record)

field containing all parameters for overloading

:= g_all_arguments (argindx_in);

Nth parameter in the program's parameter list

field containing a single row fromALL_ARGUMENTS (more or less) with the

top-level parameter information

the record that isassigned as the top-

level parameter

And then I can "query" the contentswith a minimum of code


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l_programs ('TOP_SALES') (2).EXISTS (0)

Is the TOP_SALES

program overloaded?

l_programs ('TOP_SALES') (2)(0)(0).datatype

l_programs ('TOP_SALES').COUNT > 1

Is the 2nd overloadingof TOP_SALES a

function?

What is the datatypeof the RETURN clauseof the 2nd overloading

of TOP_SALES?

And, of course, I know the beginning and end points ofeach program, overloading, and argument. I just use the

FIRST and LAST methods on those collections!

Some best practices for these complexstructures


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As you can see, you can easily and rapidlyarrive at completely unreadable and un-maintainable code.

What' s a developer to do?

Hide complexity -- and all data structures --behind small modules.

Functions to retrieve contents andprocedures to set contents.

cc_smartargs.pkb:cc_smartargs.next_overloading

cc_smartargs.add_new_parameter

Nested Tables unveil theirMULTISET-edness

Oracle10g


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Oracle10g introduces high-level setoperations on nested tables (only).

Nested tables are multisets, meaningthat theoretically there is no order to their

elements. This makes set operations ofcritical importance for manipulatingnested tables. .

You can now

Check for equality and inequality

Obtain UNION, INTERSECT and MINUS oftwo NTs

Check for equality and inequalityOracle10g


65/280


Just use the basic operators.DECLARE

TYPE clientele IS TABLE OF VARCHAR2 (64);group1 clientele := clientele ('Customer 1', 'Customer 2');group2 clientele := clientele ('Customer 1', 'Customer 3');group3 clientele := clientele ('Customer 3', 'Customer 1');

BEGINIF group1 = group2 THEN

DBMS_OUTPUT.put_line ('Group 1 = Group 2');ELSE

DBMS_OUTPUT.put_line ('Group 1 != Group 2');END IF;

IF group2 != group3 THENDBMS_OUTPUT.put_line ('Group 2 != Group 3');

ELSEDBMS_OUTPUT.put_line ('Group 2 = Group 3');

END IF;END; 10g_compare.sql

10g_compare_old.sql

UNION, INTERSECT, MINUSOracle10g


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Straightforward, with the MULTISET keyword.BEGIN

our_favorites := my_favorites MULTISET UNION dad_favorites;show_favorites ('MINE then DAD', our_favorites);

our_favorites := dad_favorites MULTISET UNION my_favorites;show_favorites ('DAD then MINE', our_favorites);

our_favorites := my_favorites MULTISET UNION DISTINCT dad_favorites;show_favorites ('MINE then DAD with DISTINCT', our_favorites);

our_favorites := my_favorites MULTISET INTERSECT dad_favorites;show_favorites ('IN COMMON', our_favorites);

our_favorites := dad_favorites MULTISET EXCEPT my_favorites;show_favorites ('ONLY DAD''S', our_favorites);

END;10g_setops.sql

10g_string_nt.sql10g_favorites.sql10g*union*.sql

Distinct sets of valuesOracle10g


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Use the SET operator to work with distinct values, and

determine ifyou have a set of distinct values.DECLARE

keep_it_simple strings_nt := strings_nt ();BEGIN

keep_it_simple := SET (favorites_pkg.my_favorites);

favorites_pkg.show_favorites ('FULL SET', favorites_pkg.my_favorites);

p.l (favorites_pkg.my_favorites IS A SET, 'My favorites distinct?');p.l (favorites_pkg.my_favorites IS NOT A SET, 'My favorites NOT distinct?');

favorites_pkg.show_favorites ('DISTINCT SET', keep_it_simple);

p.l (keep_it_simple IS A SET, 'Keep_it_simple distinct?');

p.l (keep_it_simple IS NOT A SET, 'Keep_it_simple NOT distinct?');

END;

10g_set.sql10g_favorites.pkg

Determining subsets of dataOracle10g


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Use the SUBMULTISET operator to determine if a

nested table contains only elements that are inanother nested table.

BEGINp.l (favorites_pkg.my_favorites

SUBMULTISET OF favorites_pkg.eli_favorites, 'Father follows son?');

p.l (favorites_pkg.eli_favoritesSUBMULTISET OF favorites_pkg.my_favorites

, 'Son follows father?');

p.l (favorites_pkg.my_favoritesNOT SUBMULTISET OF favorites_pkg.eli_favorites

, 'Father doesn''t follow son?');

p.l (favorites_pkg.eli_favoritesNOT SUBMULTISET OF favorites_pkg.my_favorites

, 'Son doesn''t follow father?');END; 10g_submultiset.sql

10g_favorites.pkg

The Wonderful World ofOracle Object Types


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A New Frontier:

Object Types andObject-oriented Development

in PL/SQL

Which best describes yourrelationship with Object Types?


70/280


I love 'em and use 'em all the time.

They scare me. I'll stick with good, old-fashioned relational tables.

I am comfortable with defining and using

object types, but not in production.

We use object types and haveincorporated them into our production

applications.

Object Types in Oracle


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Object types were first introduced into the

Oracle8 RDBMS (the "object-relational" model). Oracle uses object types in many of its new features

(e.g., Oracle AQ, the XML datatype).

Few development shops work with object types.

The implementation is weak. Not really object oriented.

Advantages are not persuasive to developers andDBAs with relational and procedural backgrounds.

Oracle9i support for inheritance may well change thissituation..

Some Terminology


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Object type - Oracle's version of a class; a structure that

combines data with programs (a blend of a table and apackage).

Object type instance - Oracle's version of an object

Attribute - a characteristic or "column" of the object type.

Method - a program that manipulate an object type instance. Supertype - a type that is closer in the hierarchy to the root

Subtype - a type that has a supertype.

Inheritance - the ability of a subtype to inherit attributes and

methods from a supertype. Overriding - replacing functionality of a supertype with new

functionality in a subtype.

A Very Simple Object Type Example


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The food type contains three attributes and nomethods or programs.

It is very similar to a CREATE TABLE statement,but it does not create a "container" for data. Rather

it is a "template" for data or instances.

CREATE TYPE food_tAS OBJECT (

nameVARCHAR2(100),food_group VARCHAR2(100),grown_in VARCHAR2(100)

);

Attributes

Working with Simple Objects


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DECLARE

my_favorite_vegetable food_t := food_t ('Brussel Sprouts',

'VEGETABLE','Farm,Greenhouse,Backyard');

BEGINDBMS_OUTPUT.put_line (

my_favorite_vegetable.name);

my_favorite_vegetable.food_group :='SATISFACTION';

IF INSTR (my_favorite_vegetable.grown_in,'yard')>0

THENorder_seeds (my_favorite_vegetable);

ENDIF;END;

Create a newobject with aconstructor.

Read an attributevalue

Modify anattribute value

Pass an objectas a parameter

objtype.sql

Another Object Type Example


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The timer objectcalculateselapsed time.

It consists of four

attributes andfive methods.

CREATETYPE tmr_tAS OBJECT (

startTime INTEGER,endTime INTEGER,repetitions INTEGER,nameVARCHAR2(2000),

MEMBERPROCEDUREgo,

MEMBERPROCEDUREstop( show_timing INBOOLEAN:=TRUE),MEMBERFUNCTION timing RETURNINTEGER,MEMBERPROCEDURE reset (

name INVARCHAR2:=NULL),STATIC FUNCTION make (

name INVARCHAR2,

repetitions ININTEGER:=1) RETURN tmr_t);

Attributes

Methods

tmr.ot

About Constructor Functions


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Each object type

comes with its ownconstructor function.You must supply a

value for eachattribute.

Oracle9i Release 2allows you designuser-definedconstructors, so you

can hide attributesand performadditional init. tasks.

CREATETYPE tmr_tASOBJECT(...

CONSTRUCTORFUNCTION tmr_t (SELF INOUT tmr_t,name INVARCHAR2,

repetitions ININTEGER ) RETURN SELFAS RESULT);CREATEORREPLACETYPEBODY tmr_t

ASCONSTRUCTORFUNCTION tmr_t (

SELF INOUT tmr_t,name INVARCHAR2,

repetitions ININTEGER ) RETURN SELFAS RESULT IS BEGIN

SELf.repetitions := repetitions;SELF.name := name;

RETURN; END;END;

Oracle9iRelease 2

Using the Timer Object


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DECLAREonce_tmr tmr_t :=NEWtmr_t (

NULL,NULL, 10000, 'Packaged Function');

myonce_tmr tmr_t := tmr_t.make ( 'Packaged Constant',10000);

every_tmr tmr_t :=NEWtmr_t ( 'USER Function', 10000);

BEGINonce_tmr.go ();

FORindx IN1.. count_in LOOP

v:=thisuser.name;

ENDLOOP;once_tmr.stop ();

Declare timer with

default constructor

Invoke object typemethods using dot

notation.

thisuser.tst

Declare timer with"pseudo-constructor"

Declare timer with user-defined constructor

Support for inheritance in object typesOracle9i


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You can now define a hierarchy of subtypes ofobject types.

A subtype contains all the attributes andmethods of the parent type (or supertype).

The subtypes can also contain additionalattributes and additional methods, and canoverride methods from the supertype.

You decide if an object type is INSTANTIABLE

or is FINAL (cannot be extended to a subtype).

Type Hierarchy ExampleOracle9i


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An employee is one sort of person. An hourlyworker is one sort of employee. An employee isalways a person, but a person may not be anemployee.

Person

Citizen

Corporation

Employee

supertype/"wider" subtype/"narrower"

Hourly Worker

SalariedWorker

Management

Non-Management

"root" type

person.ot

Why Bother with Hierarchy?


80/280


Define shared functionality once at the"widest" level and it is automatically availableat all narrower points in the hierarchy.

A very powerful approach to code reuse.

Easily customize or override functionality forspecific subtypes.

You get the best of both worlds: rely on the

supertype-standard, and selectively over-ride thatfunctionality as needed.

Let's Build a Type HierarchyOracle9i


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We have a three levelhierarchy: food is the root type.

desserts are a type of food

cakes are a type of dessert. We will make cake the most

specialized type of foodallowed in the hierarchy.

food

dessert

cake

"root",supertypeof dessert

subtype offood,supertypeof cake

subtypeof dessert

food.ot

Creating a SimpleObject Type Hierarchy


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CREATE TYPE food_t AS OBJECT (name VARCHAR2(100),food_group VARCHAR2 (100),grown_in VARCHAR2 (100))

NOT FINAL;

CREATE TYPE dessert_t UNDERfood_t (contains_chocolate CHAR(1),year_created NUMBER(4))

NOT FINAL;

CREATE TYPE cake_t UNDERdessert_t (diameter NUMBER,inscription VARCHAR2(200));

NOT FINAL

indicates that thistype can be asupertype.

UNDER denotesthat this type is asubtype.

An object instantiated from food_t has three attributes. A dessertobject has five attributes. A cake has seven.

food.ot

Substitutability ofObject Types


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A supertype is substitutable if one of itssubtypes can substitute or stand in for it ina slot (a variable, column, etc.) whosedeclared type is the supertype.

Oracle supports object type substitution in

columns of relational tables, attributes ofobject types and elements in collections.

"Any object of type cake is also a dessert,

is also a food."

Populate an Object Table


84/280


Create a table of objects of type food (root type).

Populate it with objects at different levels in hierarchy.DECLARE

my_favorite_vegetables food_t :=food_t ('Brussel Sprouts','VEGETABLE','farm');

BEGIN INSERTINTOsustenanceVALUES(my_favorite_vegetables);

INSERTINTOsustenanceVALUES(dessert_t ('Jello','PROTEIN','bowl','N',1887));

INSERTINTOsustenance

VALUES(cake_t ( 'Marzepan Delight','CARBOHYDRATE','bakery', 'N',1634,8,'Happy Birthday!'));END;

CREATETABLEsustenanceOF food_t;

Substitution of subtypes

Use of constructor toinitialize a variable

food.ot

Objects in a Collection


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Create a table of objects of type food (root type).

DECLARETYPE foodstuffs_nt ISTABLEOF food_t;

fridge_contents foodstuffs_nt := foodstuffs_nt (

food_t ('Eggs benedict','PROTEIN','Farm'),dessert_t ('Strawberries and cream','FRUIT','Backyard','N',2001),

cake_t ( 'Chocolate Supreme', 'CARBOHYDATE', 'Kitchen', 'Y',2001,8, 'Happy Birthday, Veva' )

);BEGIN...

Insert three different

objects in the collection,each of a different type.

Declare a nestedtable

Accessing Attributes in SubstitutedTypes


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You can substitute a subtype in a supertype

column or attribute, but subtype-specific attributesand methods are by default not visible.

SQL> DECLARE4 mmm_good food_t :=

5 dessert_t ('Super Brownie', 'CARBOHYDRATE',6 'my oven', 'Y', 1994);7 BEGIN8 DBMS_OUTPUT.PUT_LINE (mmm_good.contains_chocolate);9 END;10 /DBMS_OUTPUT.PUT_LINE (mmm_good.contains_chocolate);

*ERROR at line 8:PLS-00302: component 'CONTAINS_CHOCOLATE' must be declared

Converting Between Types


87/280


Use the TREAT operator to "treat" or convert

a wider type into a narrower subtype:

CREATE TABLE books (title VARCHAR2(30),author Person_ot /* substitutable */);

BEGININSERT INTO books

VALUES ('Oracle PL/SQL Programming',citizen_ot ('HUMAN','Steven Feuerstein',

180, '23-SEP-1958', 'USA', 'Independent'

));

END;/SELECT author.nation FROM Books; -- WILL NOT WORK!

SELECT TREAT(author AS citizen_ot).nation FROM Books; - WORKS!

treat2.sql

Use TREAT to Identify ConstrainedTypes


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/* Show all the meals in which a main course is a dessert */SELECT*

FROMmealWHERE TREAT (main_courseAS dessert_t)ISNOTNULL;

/* Will fail, since main_course is of food_t type */SELECT main_course.contains_chocolate

FROMmealWHERE TREAT (main_courseAS dessert_t)ISNOTNULL;

/* Now works, since I am treating main_course as a dessert */SELECT TREAT (main_courseAS dessert_t).contains_chocolate FROMmealWHERE TREAT (main_courseAS dessert_t)ISNOTNULL;

/* Set to NULL any desserts that are not cakes... */UPDATE meal SET dessert = TREAT (dessertAS cake_t);

treat.sql

Example: NOT SUBSTITUTABLE


89/280


The appetizer must be of type food_t;

desserts are not acceptable.SQL> BEGIN2 INSERT INTO meal VALUES (3 SYSDATE + 1,4 dessert_t ('Strawberries and cream',

5 'FRUIT', 'Backyard', 'N', 2001),6 food_t ('Eggs benedict', 'PROTEIN', 'Farm'),7 cake_t ('Apple Pie', 'FRUIT',8 'Baker''s Square', 'N', 2001, 8, NULL));9 END;10 /

BEGIN*ERROR at line 1:ORA-00932: inconsistent datatypes

notsubst.sql

Constraining Substitutability toa Specific Type


90/280


Suppose I want a column of desserts tocontain only cakes?

CREATE TABLE meal (

served_on DATE,

appetizer food_t,

main_course food_t,

dessert dessert_t

)

COLUMN appetizer NOT SUBSTITUTABLE AT ALL LEVELS,

COLUMN dessert IS OF (ONLY cake_t)

;

Unconstrainednon-substitutability

Constrain to asingle subtype

notsubst.sqlYou can only constrain to asingle type, not a list of types.

Turning Off Substitutability


91/280


Oracle provides syntax to turn off substitutability on

either an entire type or specific attributes of a type.

CREATE TABLE brunches OF food_tNOT SUBSTITUTABLE AT ALL LEVELS;

CREATE TABLE meal (served_on DATE,appetizer food_t,main_course food_t,dessert dessert_t)

COLUMN appetizer NOT SUBSTITUTABLE AT ALL LEVELS;

At the table level

For a single column

Creating "Template" Types


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Some object types should only be used assupertypes for other types; they are so general, youwould not actually create and manipulate instancesfrom those types.

Oracle allows you to define object types as NOTINSTANTIABLE, as shown above.

CREATE TYPE Address_t ASOBJECT (

street VARCHAR2(1000),city VARCHAR2(30),...

)NOT INSTANTIABLENOT FINAL;

Creating and Overriding Methods


93/280


Most real-world object types will have bothattributes and methods, programs thatperform operations on attributes.

With inheritance, you can:

inherit supertype methods override or replace supertype methods with

subtype implementations

add completely new methods

Overriding to Provide Specificity forSubtypes

CREATE OR REPLACE TYPE BODY dessert t


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Different

calculations fordesserts andcakes.

CREATE OR REPLACE TYPE BODY cake_tIS

OVERRIDING MEMBERFUNCTION price RETURN NUMBERISBEGIN

RETURN (5.00

+ 0.25 * (LENGTH (SELF.inscription))+ 0.50 * diameter);END;

END;

Generic dessert prices aredetermined by chocolate

content and age. Cake prices

are driven by inscriptionlength and size..

food2.ot

CREATE OR REPLACE TYPE BODY dessert_tIS

OVERRIDING MEMBERFUNCTION price RETURN NUMBER ISmult NUMBER := 1;

BEGINIF SELF.contains_chocolate = 'Y'

THEN mult := 2; END IF;IF SELF.year_created < 1900

THEN mult := mult + 0.5; END IF;RETURN (10.00 * mult );

END;END;

Disallowing Overrides


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If you do not want a subtype to modify thebehavior of a supertype method, declare it tobe FINAL. You can do this even in object types that are

NOT FINAL.

CREATE TYPE Person_t ASOBJECT (

ssn NUMBER,name VARCHAR2(30),address VARCHAR2(100),

FINAL MEMBER PROCEDURE showInfo)NOT FINAL;

Requiring Overrides to Methods

CREATE TYPE food t AS OBJECT ( food2.ot


96/280


Suppose the implementation of a method changes witheach subtype in the hierarchy andthe supertype'simplementation really is irrelevant.

Declare the method to be NOT INSTANTIABLE and then

(a) you do not have to provide an implementation of themethod and (b) all subtypes mustprovide animplementation.

_ (name VARCHAR2(100),

food_group VARCHAR2 (100),grown_in VARCHAR2 (100),NOT INSTANTIABLE MEMBER

FUNCTION price RETURN NUMBER)NOT FINAL

NOT INSTANTIABLE;

If any member is NOTINSTANTIABLE, then the

entire type must bedeclared the same way.

food2.ot

Quiz: What is "Dynamic Polymorphism"?

A new kind of diet regimen


97/280


A new kind of diet regimen.

A form of sex therapy practiced inLuxembourg.

A computer language's ability to anticipatethe requirements of a system and generatematching code.

A computer language's ability to choose atrun-time among different forms of the same

program.

About Polymorphism


98/280


The ability to choose from multiple methods of thesame name and execute the appropriate method. Static polymorphism: the decision about which method to

execute is made at the time the code is compiled. Staticpolymorphism is also known as overloading, and is

supported in declaration sections of PL/SQL blocks. Dynamic polymorphism: the decision about which method to

execute is made at the time the code is executed, at run-time. This is also known as "dynamic method dispatch", andis available for the first time in PL/SQL with support forobject type inheritance.

Exploring Dynamic Polymorphism


99/280


CREATETYPE food_tAS OBJECT(

...attributes...MEMBERFUNCTION price RETURNNUMBER)NOT FINAL;

CREATETYPE dessert_t UNDERfood_t ( ...attributes...

OVERRIDING MEMBERFUNCTION priceRETURNNUMBER

)NOT FINAL) ;CREATETYPE cake_t UNDERdessert_t ( ...attributes... -- No price method of its own.

);

The food anddessert typeseach have a pricemethod, but cake

does not. It simply inherits

the dessertmethod.

A Visual Representation

The root price


100/280


The root price

function is over-ridden in thedessert subtype.

The cake

subtype nowsimply inheritsits pricecalculation from

its dessertsupertype.

food

dessert

cake

Price

Price

the "original"

An override

Inherited

calculation

Dynamically Choosingthe Right Method

DECLARE


101/280


DECLARETYPE foodstuffs_nt IS TABLE OF food_t;

fridge foodstuffs_nt:= foodstuffs_nt (

food_t ('Eggs benedict', ...), dessert_t ('Strawberries and cream', ...), cake_t ('Chocolate Supreme', ...));BEGIN

FOR indx INfridge.FIRST ..fridge.LAST

LOOPDBMS_OUTPUT.put_line (

'Price of ' || fridge (indx).NAME ||' = ' ||

fridge (indx).price);END LOOP;

END;

A collection of foods ispopulated with threedifferent object types.

The price invocation isresolved at run-time, andnot necessarily as thefood_t.price method.

food3.ot

food4.otdynpoly_overhead.tst

Object Types Summary

They are finally becoming robust enough to


102/280


They are finally becoming robust enough to

be useful Object types are being used extensively by

Oracle itself.

This fact makes more confident of the future,performance and capabilities of object types.

Get familiar with the syntax so that you canwork with object types with confidence.

New and Enhanced Datatypes inOracle9i


103/280


TIMESTAMP and INTERVAL XMLType

The ANY* "generic" types

Timestamps & Intervals

TIMESTAMP


104/280


TIMESTAMP

Extends the DATE datatype, offering a muchhigher (and variable) precision of seconds.

INTERVAL Store and manipulate intervals of years and

months. DAY TO SECOND: represent the precise

difference between two datetime values.

YEAR TO MONTH: calculate the difference

between two datetime values, where the onlysignificant portions are the year and month.

Timestamp Precision

DECLARE


105/280


When you declare a TIMESTAMP, you

provide a precision (from 0 to 9) for theseconds component of the value.

Use TIMESTAMP WITH TIME ZONE to

handle time zone displacement.

checkout TIMESTAMP(3);

BEGINcheckout := '1999-06-22 07:48:53.275';

...

END;

Working with Time Zones

DECLARE

logoff TIMESTAMP(3) WITH TIME ZONE;

logon TIMESTAMP(3) WITH LOCAL TIME ZONE;


106/280


Automatically work with the local time zone or specify aspecific displacement.

Useful when gathering data that crosses time zones.

The TIMEZONE_REGION and TIMEZONE_ABBRcolumns of the V$TIMEZONE_NAMES data dictionaryview provide the names of available time zones.

logon TIMESTAMP(3) WITH LOCAL TIME ZONE;

BEGIN

logoff := '1999-10-31 09:42:37.114 +02:00';

...

END;

tzset_show.sqltzmisc.sql

tzglobal_events_local.sql

Interval Computations

In the example below declare a variable of type


107/280


In the example below, declare a variable of type

INTERVAL YEAR TO MONTH, then assign a valueof 101 years and 3 months to it in three differentways. These are notpoints in time, but amounts of elapsed time.

DECLARE

lifetime INTERVAL YEAR(3) TO MONTH;

BEGIN

lifetime := INTERVAL '101-3' YEAR TO MONTH; -- interval literal

lifetime := '101-3'; -- implicit conversion from character type

lifetime := INTERVAL '101' YEAR; -- Can specify just the years

lifetime := INTERVAL '3' MONTH; -- Can specify just the months

...END;

Function with Interval

MEMBER FUNCTION RETURN INTERVAL YEAR TO MONTH


108/280


Notice the explicit conversion of the agecalculation formula to an INTERVAL.

MEMBER FUNCTION age RETURN INTERVALYEAR TO MONTH

ISretval INTERVAL YEAR TO MONTH;

BEGINretval := (SYSDATE - SELF.dob)YEAR TO MONTH;

RETURN retval;END;

person.ot

Lots of New Functions

New conversion and "right now" capabilities:


109/280


New conversion and right now capabilities:

EXTRACT

NUMTODSINTERVAL

NUMTOYMINTERVAL

TO_DSINTERVAL

TO_YMINTERVALTO_TIMESTAMP

TO_TIMESTAMP_TZ

FROM_TZ

SESSIONTIMEZONE

CURRENT_DATE

CURRENT_TIMESTAMP

DBTIMEZONELOCALTIMESTAMP

SYSTIMESTAMP

TZ_OFFSET

extract.sql

Working with XML in PL/SQL


110/280


Brief introduction to XML

The XMLtype datatype

What is XML?

Stands for Extensible Markup Language and


111/280


p g g

defines a universal standard for electronic dataexchange...."EDI for the 21st century"

Offers a rigorous set of rules to give structure todata and make it easy to send and receive

information. Nothing but "text with tags"... a vendor-neutral,

platform-neutral, standards-based informationpathway.

Simple XML Example

70689

h k l /


112/280


ThickPlating, Inc.

Waste dumped in river

Chimney filters disabled

Press conference to call for fines and penalties.

File suit in state and federal counts.

Why Use XML?

XML can serve as application integration "glue"


113/280


XML can serve as application integration glue .

XML over the HTTP protocol may provide the technology torelatively seamlessly and inexpensively connectheterogeneous databases, applications and networks.

XML makes it easier to publish and reuse information.

Complete separation of data from presentation layer. Standard utilities to transform data to specific output styles.

XML is extensible. "Roll your own" markup language.

Extensions to XML

XML is tabula rosa.


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You get to define the tags (you can think of HTML as asubset of XML with pre-defined formatting tags).

Different industries are now defining standardizedmarkup languages that know about those

industries' requirements. Some examples: ebXML electronic business infrastucture

WML wireless markup language

docBook documentation standards

www.xml.org

Send/Receive XML over Internet

You can easily send XML documents over the Web


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using: FTP - File Transfer Protocol (transfer files)

SMTP - Simple Mail Transfer Protocol (transfer email)

HTTP - HyperText Transfer Protocol (transfer documents)

XML will likely figure prominently in the explosion ofwireless Internet devices. "Small footprint" of information-rich data.

Oracle 8iWeb

XML


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XML and HTTP can connect heterogeneous applications

SQLServer

XSLTStylesheet

OracleAppsSAP

Apps MessageHub

XML

XML

XMLWeb

Oracle Support for XML

Oracle has moved very aggressively to


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Oracle has moved very aggressively to

support XML from both Java and PL/SQL. Started in Oracle8i and accelerated tremendously

in Oracle9i: the XDB

JDeveloper allows you create, syntax-checkand debug XML, XSLT and XSQL.

interMedia lets you index and search an XMLdocument.

Many utilities available through PL/SQL (nextpage).

Some Oracle XML Components

Download the Oracle XDK from the Oracle TechnologyNetwork; the 9i XDK works for 8i as well.


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XML Parser Use it to parse, construct and validate XMLdocuments.

XPath Engine A utility that searches in-memory XML documentsusing the declarative syntax of XPath, anotherelement of the XML standard

XSLTProcessor

Supports XSLT in Oracle, allowing you totransform XML documents into different formats

XML SQLUtility

Utility to facilitate the production of XMLdocuments from SQL and to easily insert XML-based data into Oracle tables.

XSQL Pages Technology allowing you to assemble XML datadeclaratively and then publish that data with XSLT.

Some XML Concepts and Capabilities

The XML Document


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Document Type Definitions andSchemas

Similar to DDL for tables, DTDs and schemasdefine valid syntax for an XML document

The XML Infoset Tree representation of XML document

XPath

Search contents of XML documents

From Document to Infoset

/

Text DocumentInformation Set/


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89-344

WEBMINTC

XMLParser

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Shares = 100

WEBM

Shares = 30

INTC

XPath: The XML Search Syntax

W3C offers a declarative language called


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XPath to query the contents of an XMLdocument.

Operators on an information set

Leverages our familiarity with the hierarchicalstructure and path notation of directories andURLs.

The Oracle xslProcessor package

implements the XPath functionality.

Some XPath Examples

What are the names of the newspaper in thedocument?


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/Newspaper/Name

Does this company's CEO have any bonuspayments over $100,000 while hiring of new

employees was frozen?

//CEO/Bonus[. > 100000 and @HiringFreeze="ON"]

When did Sheri S. Tepper publish "Grass" ?

/Publication/Novel[Title="Grass"]/@PublicationDate

The New XML Datatype

A system-defined object type that has

Oracle9i


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predefined member functions available toextract XML nodes and fragments.

Brings the XML and SQL worlds together

SQL operations on XML content XML operations on SQL content

Apply standard XML functionality, such as XPath,directly against data without need to convert.

Set of XMLtype Methods

createXML: creates an XMLtype instance from a stringor CLOB

Oracle9i


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or CLOB. existsNode: returns 1 if the given XPath expression

returns any result nodes. extract: applies an XPath expression over the XML data

to return a XMLType instance containing the resultantfragment.

isFragment: returns 1 if the XMLtype contains afragment.

getCLOBval, getStringval, getNumberval: returns anXML document or fragment as CLOB, string or number.

Transfer XML Docs to Tables

Create a table with an XMLtype column and

Oracle9i


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insert values with the CreateXML procedure.CREATE TABLE xml_tab (xmlval SYS.XMLTYPE);

INSERT INTO xml_tab VALUES (SYS.XMLTYPE.CREATEXML('

221 John '));

INSERT INTO xml_tab VALUES (XMLTYPE ('

331 PO_1 '));

xmltype.sql

Oracle9iRelease 1 Syntax

Oracle9iRelease 2 Syntax

Retrieve XML Data

SQL> select x.xmlval.getstringval() from xml_tab x;

Oracle9i


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Note: you must use an alias on the table name.

X.XMLVAL.GETSTRINGVAL()---------------------------------------------------------

221John

331PO_1


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Updating XML Documents in Tables

Use updateXML to change the contents of an


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XML document in a table.The following statement updates all rowsthat have an employee element with the newvalues.

UPDATE emp_tab e SET e.emp_col = UPDATEXML (e.emp_col, '/EMPLOYEES/EMP[EMPNAME="Joe"]/SALARY/text()',100000, '//EMP[EMPNAME="Jack"]/EMPNAME/text()','Jackson',

'//EMP[EMPNO=217]', XMLTYPE.CREATEXML( '217

Jane'))WHERE EXISTSNODE(e.emp_col,'//EMP')=1;


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Data Types - Summary

A broader, deeper choice for data types and


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data structures offers great potential forimproving the quality and reducing thequantity of your code base.

Potentially dramatic impact on the quality ofyour code.

Get comfortable with the structures and putthem to work for you.

SQL-Related Enhancements in PL/SQL

Native Dynamic SQL


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Bulk processing of DML and queries

Record-based DML

Autonomous transactions

Table functions and CURSOR expressions


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The Beauty and Eleganceof

Native Dynamic SQL

What is Dynamic SQL?

Dynamic SQL actually refers, in the world of


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PL/SQL, to two things: SQL statements, such as a DELETE or CREATE

TABLE, that are constructed and executed at run-time.

Anonymous PL/SQL blocks that are constructed,compiled and executed at run-time.

'DROP ' ||l_type || ' ' || l_name

'BEGIN ' ||l_proc_name || ' (' ||l_parameters || '); END;'

The Possibilities of Dynamic SQL

Build ad-hoc query and update applications.


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When the user gets to decide what to do and see...acommon requirements for Internet applications.

Execute DDL statements from within PL/SQL. They are not otherwise available in a PL/SQL block.

Construct very generic and highly useful utilitiesthat work on "any" table or data structure.

Optimize SQL statements at run-time through soft-coding of hints.

Two Methods Available

DBMS_SQL


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A large and complex built-in package that madedynamic SQL possible in Oracle7 and Oracle8.

Native Dynamic SQL

A new (with Oracle8i), native implementation ofdynamic SQL that does almostall of whatDBMS_SQL can do, but much more easily andusually more efficiently.

Let's focus on Native Dynamic SQL or NDS.

Native Dynamic SQL

The new "native dynamic SQL" or NDS of


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Oracle8i is implemented with just twostatements (which are part of the language andnot available via a built-in package): EXECUTE IMMEDIATE , used for DDL,

DML and single row fetches. OPEN FOR , used for multi-row queries.

And in Oracle9i Release 2, you can

even use EXECUTE IMMEDIATEfor multi-row queries!

EXECUTE IMMEDIATE

EXECUTE IMMEDIATE sql-string

[INTO {define_variable[, define_variables]... | record }]


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Use this statement to execute any dynamic SQLstatement (including a PL/SQL block) exceptfor multi-row

queries. The INTO clause allows you to pass values from the

select list of a single row query into local variables,including objects, collections and records.

The USING clause allows you to specify bind arguments

or variables to be passed into the SQL string beforeexecution.

[USING {IN | OUT | IN OUT] bind argument

[, {IN | OUT | IN OUT] bind argument]...];

DDL within PL/SQL

Very easy, very dangerous with NDS.

H ' d th t "d h t "


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Here's a procedure that "drops whatever".CREATE OR REPLACE PROCEDURE drop_whatever (nm IN VARCHAR2)

AUTHID CURRENT_USERIS

CURSOR type_cur IS

SELECT object_type FROM USER_OBJECTSWHERE object_name LIKE UPPER (nm);type_rec type_cur%ROWTYPE;

BEGINOPEN type_cur; FETCH type_cur INTO type_rec;IF type_cur%FOUND THEN

EXECUTE IMMEDIATE'DROP ' || type_rec.object_type || ' ' || nm;

END IF;END;

dropwhatever.spcreind81.sphealth$.pkgsettrig.sp

COUNT(*) For Any Table

Here's a handy and simple utility based onNDS:

CREATE OR REPLACE FUNCTION tabCount (tab IN VARCHAR2, whr IN VARCHAR2 := NULL, sch IN VARCHAR2 := NULL)RETURN INTEGER

IS


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IF tabCount ('citizens', 'insured = ''NO''') > 40,000,000THEN

DBMS_OUTPUT.PUT_LINE ('Not the best health care system in the world....');

END IF;tabcount81.sftabcount.sf

ISretval INTEGER;

BEGINEXECUTE IMMEDIATE

'SELECT COUNT(*) FROM ' || NVL (sch, USER) ||'.' || tab || ' WHERE ' || NVL (whr, '1=1') INTO retval;

RETURN retval;

END;

Specify schema, table andWHERE clause...

DML with NDS

CREATE OR REPLACE PROCEDURE salary_raise ( raise_percent NUMBER, job VARCHAR2)IS

TYPE loc arra t pe IS TABLE OF offices location@TYPE


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TYPE loc_array_type IS TABLE OF offices.location@TYPEINDEX BY BINARY_INTEGER;

dml_str VARCHAR2 (200);loc_array loc_array_type;

BEGINSELECT location BULK COLLECT INTO loc_array

FROM offices;

FOR i IN loc_array.FIRST .. loc_array.LAST LOOPdml_str := 'UPDATE emp_' || loc_array (i)

|| ' SET sal = sal * (1+(:raise_percent/100))'|| ' WHERE job = :job_title';

EXECUTE IMMEDIATE dml_str USING raise_percent, job;

END LOOP;END;

Differenttable for

each location

Works w/User-defined types

In the following example, the USING clause allows

t bj t d t d t bl t


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PROCEDURE add_profit_source (

hosp_name IN VARCHAR2,pers IN Person,cond IN preexisting_conditions)

ISBEGIN

EXECUTE IMMEDIATE'INSERT INTO ' || tabname (hosp_name) ||

' VALUES (:revenue_generator, :revenue_inhibitors)'USING pers, cond;END;

me to pass an object and nested table to anINSERT statement with a variable table name. Completely transparent support.

health$.pkg

Multiple Row Queries and NDS

Familiar syntax, tiny learning curve: OPEN FOR Here is a simple utility that displays the values of any date,

number or string column in any table


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number or string column in any table.

CREATE OR REPLACE PROCEDURE showcol (tab IN VARCHAR2, col IN VARCHAR2, whr IN VARCHAR2 := NULL)

IScv SYS_REFCURSOR; -- Available in Oracle9i

val VARCHAR2(32767);

BEGIN OPEN cv FOR 'SELECT ' || col || ' FROM ' || tab ||

' WHERE ' || NVL (whr, '1 = 1');LOOP

FETCH cv INTO val;EXIT WHEN cv%NOTFOUND;DBMS_OUTPUT.PUT_LINE (val);

END LOOP;CLOSE cv;

END;

showcol81.spndsutil.pkg

Fetch Into Records!

In DBMS_SQL, you had to write many tediouslines of code to fetch into individual variables.


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CREATE OR REPLACE PROCEDURE showemps (where_in IN VARCHAR2 := NULL)IS

cv SYS_REFCURSOR;rec employee%ROWTYPE;

BEGIN OPEN cv FOR

'SELECT * FROM employeeWHERE ' || NVL (where_in, '1=1');

LOOPFETCH cv INTO rec;EXIT WHEN cv%NOTFOUND;DBMS_OUTPUT.PUT_LINE (

TO_CHAR(rec.employee_id) || '=' || rec.last_name);

END LOOP;CLOSE cv;

END;

New (Oracle9i) pre-defined weak REF

CURSOR type

Quiz!

PROCEDURE process_lineitem( line_in ININTEGER)IS

BEGINIF li i 1

What's wrong with

this code?


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BEGIN IF line_in =1 THEN

process_line1; ENDIF;

IF line_in =2

THENprocess_line2; ENDIF;

... IF line_in =22045 THEN

process_line22045; ENDIF;END;

dynplsql.txt

this code? How would you fix

it?

From 22,000 lines of code to 1!PROCEDURE process_lineitem( line_in ININTEGER)ISBEGIN IF line_in =1

THEN

PROCEDURE process_lineitem (

line in IN INTEGER)IS


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Identify the pattern andresolve it either withreusable modules or

dynamic abstractions.

THENprocess_line1;

ENDIF;

IF line_in =2 THEN

process_line2;

ENDIF;...

IF line_in =22045 THEN

process_line22045; ENDIF;END;

line_in ININTEGER)ISBEGIN EXECUTEIMMEDIATE

'BEGIN process_line'||line_in ||'; END;';

END;

dynplsql.txt

Dynamic PL/SQL with NDS

Dynamically construct, compile and run ananonymous block with EXEC. IMMEDIATE.


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DBMS_JOB uses dynamic PL/SQL to runstored procedures at scheduled times.

DECLAREv_jobno INTEGER;

BEGINDBMS_JOB.submit (job => v_jobno,what => 'DBMS_DDL.ANALYZE_OBJECT ' ||

'(''TABLE'',''LOAD1'',''TENK''' ||',''ESTIMATE'',null,estimate_percent=>50);',

next_date => TRUNC (SYSDATE + 1),

interval => 'TRUNC(SYSDATE+1)');END;

Rules for Dynamic PL/SQL

You must construct and execute a validanonymous block.

B i ith BEGIN DECLARE


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Begins with BEGIN or DECLARE.

Ends with END;. The trailing semi-colon isrequired; otherwise it is parsed as