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7/27/2019 day1 session1

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Entry Level Technology Program

Satyam Learning Center ORACLE

ORACLE

Introduction


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ORACLEOak Ridge Automated Computer

And Logical Engine

It is a DBMS, which manages a large amount of data ina multi user environment so that many users

concurrently access the data. It Also provides security

and Recovery. It stores and manages data using

relational model.

Oracle is the name of database management system

developed by Oracle corporation.


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ORACLE

Oracle server manages data in the database. Users

access Oracle server using SQL commands. So Oracle

server receives SQL commands from users and execute

them on the database.

ORACLE SERVER

Database

CLIENT

CLIENT

SQL commands

Result


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DATABASE ARCHITECTURE

LOWER LEVEL STRUCTURE PL

LL

VL

..

..

..

..

..

..

..

..

..

U1 U2

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SHADOW

PAGE

T1 T2


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Physical Level

The Physical structure of the database is placed in

Physical level. It is physically a set of operating system

files. There are 3 types.

Data Files

Redo log files

Control files

These files automatically creates when database iscreated.


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Physical structure

Data Files It contains the data of the database. Every

table that is stored in the database is a part of these

files. Only Oracle Server can interpret these data files.

Redo Log Files Every database has a set of two or

more Redo Log files. The set of redo log files is known

as databases redo log.

Redo Log files are used in failure recovery.

All changes made to the database are written to redo

log file.. ( filenames redo01.log)


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Physical Structure

Control Files Every Oracle database has a control file.

It contains vital data regarding the database. It

contains ( Extension of file is ctl)

Database Name

Names and locations of data files and redo log files.

Path Oracle\oradata\orcl ( to see all the 3 types of

files)


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Logical Structure

Logical Structure is independent of Physical structure.

Each Oracle database contains the following components.

oTablespaces

oSegments

oExtents

oBlocks


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Tablespace

Each Database is a collection of tablespaces.For example

we can use a table space called PAYROLL to store all the

data related to payroll application.

Every database contains SYSTEM tablespace. This isautomatically created when a database is created.

SYSTEM tablespace contains the data dictionary tables.

It is possible to make tablespace temporarily unavailable

by making it off-line and make it available again bychanging it to on-line.By making a tablespace off-line,

DBA can take the backup.


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SEGMENTS

Data into tablespaces comes in the form of segments.

Example Table is a segment

An Oracle database requires upto 4 types of segments

Data segments It is used to store data of tables

Index Segments used to store indexes

Rollback segments Here Undo information is stored

Temporary segments Oracle stores Temporary

tables


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Extents

The storage space is allocated to segments is in the formof Extents.Each Tablespace contains 65536 data files

N number of such Table spaces creates a database.

An extent is made with in a data fileN Number of continuous db blocks make up an Extent

Table

Table Segment

Extents

Tablespace


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QUERY PROCESS

CLIENT

DBSERVER PROCESS

CLIENT

PROCESS

1

2

31 PARSING

2 EXECUTE

3 FETCH


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Oracle Instance

.

Every oracle database is associated with an Oracle

Instance. Every time a database is started, a memory area

called System Global Area(SGA) or Shared Global Area

is allocated and one or more processes are started.

The combination of SGA and Oracle processes is called

as Oracle Instance.


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Features & Benefits

9i

ORACLE

INTERNET

Scalability

Reliability

Single Dev Model

Common Skill Sets

One Management

Interface


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Features

Oracle Offers a comprehensive high performance

infrastructure for e-business.It is called Oracle9i.It provides

every thing needed to develop, deploy and manage Internet

Applications.

Benefits

Scalability from departments to enterprise e-business sites

Reliable, available and secure architecture

One development model, easy development options

Common skill sets including SQL, PL/SQL,JAVA and

XML

One Management interface for all applications


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9i Products

9i

IAS

9i

DATABASE

There are two products. They provide a complete and

simple infrastructure for internet applications.


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Application Server

9i Application server runs all the applications and 9i

database stores our data.

Oracle 9i Application server runs

Portals or web sites

Java Transactional Applications

Provides integration between users, applications and data


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Oracle9i : OORDBMS

User-Defined data types and objects

Fully compatible with relational database

Support of multimedia and Large objects

It also support client server and web based applications

Oracle 9i can scale tens of thousands of concurrent users

and support up to 512 petabytes of data ( A peta byte is1000 tera bytes)


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Environment

Oracle uses two types of Environments for executing ourSQL statements. SQL*plus and iSQL*plus.

iSQL*plus is

oAn EnvironmentoOracle proprietary

oKeywords can be abbreviated

oRuns on a browser

oCentrally loaded, does not have to be implemented on

each machine


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Tools of Oracle

SQL * PLUS

ISQLPLUS PL/SQL

FORMS

REPORTS


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SQL commands

Data Definition Language (DDL) : CREATE, ALTER,DROP, TRUNCATE

Data Manipulation Language (DML) : INSERT, UPDATE,

DELETE

Transaction Control Language (TCL) : COMMIT,ROLLBACK, SAVEPOINT

Data Retrieval Language (DRL) : SELECT

Data Control Language (DCL) : GRANT, REVOKE


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Data Types

Data Type DescriptionVARCHAR2(size) Variable-length character data(4000bytes)

CHAR (size) Fixed-length character data up to 2000chars

NUMBER (p,s) Variable-length numeric data

DATE Date and time values

LONG Variable-length character data upto 2

GB

CLOB Character data up to 4 GB

RAW and LONG RAW Raw binary data (Raw is 2000 bytesand Long Raw is 4 GB)


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Data Types

BLOB Binary data up to 4 GB

BFILE Binary data stored in anexternal file up to 4GB

NVARCHAR2(size) Variable-length characterdata(4000 bytes/chars)depending upon NationalCharacter Set

TIMESTAMP (precision) Date plus time


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Writing BasicSQL SELECT Statements


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Basic SELECT Statement

SELECT *|{[DISTINCT] column|expression [alias],...}

FROM table;

SELECT identifies what

columns

FROM identifies which

table


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SELECT *FROM DEPT;

Selecting All Tables and Columns

SELECT *FROM TAB;

DESC[RIBE] DEPT

SELECT DEPTNO,LOC

FROM DEPT;


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Writing SQL Statements

SQL statements are not case sensitive.

SQL statements can be on one or more lines.

Keywords cannot be abbreviated or splitacross lines.

Clauses are usually placed on separate lines.

Indents are used to enhance readability.


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Using Arithmetic Operators

SELECT ENAME, SAL, SAL + 300

FROM EMP;


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Defining a Null Value

nullis a value that is unavailable, unassigned, unknown, orinapplicable.

A null is not the same as zero or a blank space.

SELECT ENAME, JOB, SAL, COMM

FROM EMP;

Null Values


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SELECT ENAME, 12*SAL*COMMFROM EMP;

Null Valuesin Arithmetic Expressions

Arithmetic expressions containing a null valueevaluate to null.


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Defining a Column Alias

A column alias:

Renames a column heading

Is useful with calculations Immediately follows the column name - there can

also be the optional AS keyword between the

column name and alias

Requires double quotation marks if it containsspaces or special characters or is case sensitive


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Using Column Aliases

SELECTEENAME "Name", SAL*12 "Annual Salary"

FROM EMP;

SELECT ENAME AS name , COMM commission

FROM EMP;


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Concatenation Operator

A concatenation operator:

Concatenates columns or character strings toother columns

Is represented by two vertical bars (||)

Creates a resultant column that is a character

expression


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Using the ConcatenationOperator

SELECT ENAME || JOB AS "Employees"

FROM EMP;


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Literal Character Strings

A literal is a character, a number, or a dateincluded in the SELECT list.

Date and character literal values must beenclosed within single quotation marks.

Each character string is output once for eachrow returned.


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Using Literal CharacterStrings

SELECT ENAME ||' is a ' ||JOBAS "Employee Details"

FROM EMP;


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Duplicate Rows

The default display of queries is all rows, includingduplicate rows.

SELECT DEPTNO

FROM EMP;


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Eliminating Duplicate Rows

Eliminate duplicate rows by using the DISTINCT keywordin the SELECT clause.

SELECT DISTINCT DEPTNO

FROM EMP;


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Restricting and Sorting Data


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Objectives

After completing this lesson, you should be able todo the following:

Limit the rows retrieved by a query

Sort the rows retrieved by a query


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Limiting the Rows Selected

Restrict the rows returned by using the WHERE clause.

The WHERE clause follows the FROM clause.

SELECT *|{[DISTINCT] column|expression [alias],...}FROM table

[WHERE condition(s)];

U i h Cl


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Using theWHERE Clause

SELECT EMPNO, ENAME, JOB, DEPTNO

FROM EMP

WHERE DEPTNO = 30 ;


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Character Strings and Dates

Character strings and date values are enclosed in singlequotation marks.

Character values are case sensitive, and date values areformat sensitive.

The default date format is DD-MON-RR.

SELECT ENAME, JOB, DEPTNO

FROM EMP

WHERE ENAME = 'WARD';


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Comparison Conditions

Operator

=

>

>=

=10000

AND JOB LIKE '%MAN%';

Using the OR Operator


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Using the OROperator

OR requires either condition to be true.

SELECT EMPNO, ENAME, JOB, SAL

FROM EMP

WHERE SAL >= 10000

OR JOB LIKE '%MAN%';

Using the NOT Operator


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SELECT ENAME, JOB

FROM EMP

WHERE JOB

NOT IN (MANAGER', 'CLERK', 'SALESMAN');

Using theNOT Operator

Rules of Precedence


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Rules of Precedence

Override rules of precedence by using parentheses.

Order Evaluated Operator

1 Arithmetic operators

2 Concatenation operator

3 Comparison conditions4 IS[NOT]NULL, LIKE, [NOT]IN

5 [NOT] BETWEEN

6 NOT logical condition

7AND

logical condition

8 ORlogical condition

Rules of Precedence


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SELECT ENAME, JOB, SAL

FROM EMP

WHERE JOB = 'SALESMAN'

OR JOB = 'PRESIDENT'

AND SAL > 15000;

Rules of Precedence

Rules of Precedence


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SELECT ENAME, JOB, SAL

FROM EMP

WHERE (JOB = 'SALESMAN'

OR JOB = 'PRESIDENT')

AND SAL > 15000;

Rules of Precedence

Use parentheses to force priority.

Cl


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SELECT ENAME, JOB, DEPTNO, HIREDATE

FROM EMP

ORDER BY HIREDATE ;

ORDER BY Clause

Sort rows with the ORDER BY clause

ASC: ascending order, default

DESC: descending order

The ORDER BY clause comes last in the SELECT statement.

Sorting in Descending Order


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Sorting in Descending Order

SELECT ENAME, JOB, DEPTNO, HIREDATE

FROM EMP

ORDER BY HIREDATE DESC ;

Sorting by Column Alias


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Sorting by Column Alias

SELECT EMPNO, ENAME, SAL*12 annsal

FROM EMP

ORDER BY annsal;

Sorting by Multiple Columns


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The order ofORDER BY list is the order of sort.

You can sort by a column that is not in theSELECT list.

SELECT EMPNO, DEPTNO, SAL

FROM EMP

ORDER BY DEPTNO, SAL DESC;

Summary


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Summary

SELECT *|{[DISTINCT] column|expression [alias],...}

FROM table

[WHERE condition(s)][ORDER BY {column, expr, alias} [ASC|DESC]];

In this lesson, you should have learned how to: Use the WHERE clause to restrict rows of output

Use the comparison conditions

Use the BETWEEN, IN, LIKE, and NULL conditions

Apply the logical AND, OR, and NOT operators

Use the ORDER BY clause to sort rows of output

Exercise


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Exercise

1) Display the names with single word 2) Display the names with two words 3) Display the names with exactly three words 4) Display all the salaries beginning with digit 2 5) Display all the names with second letter as A

6) Display the employees who joined between any two givendates

7) Display the names and experience of all the employees 8) How many employees does not draw salary between 5000

and 10000 9) Display all the names whose names contain underscore(_) 10)Calculate the experience in years for each employee and display along with their names, in descending order.

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