css/416 data design and retrieval workshop 3. css/416 workshop 32 database management systems...

CSS/416

Data Designand Retrieval

Workshop 3

CSS/416 Workshop 3 2

Database Management Systems

Terminology

Traditional MIS RDBMS

RelationalAlgebra

File Table RelationRecord Row TupleField Column Attribute


Database management Systems Relational model

Based on 1970 paper by E.F. Codd User sees all data in tables Tables can be combined using “set”

operations (linked via columns) Metadata also stored in tables as above Logical design separate from physical

implementations


Database Management Systems Functional Dependencies

A -> B; A determines B (A is Determinant)

Partial (PK = AB, B -> C)

CustID -> Customer Name


Database Management Systems Keys

Derived from entity identifier One or more attributes (more =

composite key) Uniquely determine a row Functionally determine an entire

row’s attributes


Database management systems

SID Activity Fee100 Skiing 200150 Swimming 50175 Squash 50200 Swimming 50

Modification Anomalies (multiple themes)

- Can’t insert fact that scuba diving cost $175- Cant update swimming fee- Delete SID 100=>lose skiing data


Database Normalization Entities should have common theme Stages

First Normal form Second Third Others (BCNF, 4th, 5th, DK)

Impact on referential integrity Denormalize for performance (city, state, zip

is classic example)


Database Normalization 1st normal form – eliminate multi-

valued attributes(repeating groups) 2nd normal – no partial key

functional dependencies 3rd normal – eliminate transitive

dependencies


Database Normal FormsViolates first normal – why?

Plant Name

Eqpt Name

Plant Mgr

Eqpt Mfgr

Mfgr Addr

ethylene Final cooler, feed heater

Jim Smith

ABC Exchanger

1247 Locust

styrene Feed pump Bill Gunn XYZ Pumps

432 Broadway

styrene Feed pump Bill Gunn ABC Exchanger

1247 Locust


Database NormalizationPlant Name

Eqpt Name Plant Mgr

Eqpt Mfgr

Mfgr Addr

ethylene Final cooler Jim Smith

ABC Exchanger

1247 Locust

ethylene Feed heater Jim Smith

ABC Exchanger

1247 Locust

styrene Feed pump Bill Gunn XYZ Pumps

432 Broadway

styrene Feed heater Bill Gunn ABC Exchanger

1247 Locust

1st Normal satisfied Still violates 2nd normal– why?


Database NormalizationPlantName

Eqpt name

Eqpt Mfgr Mfgr Addr

ethylene

Final cooler

ABC Exchanger

1247 Locust

ethylene

Feed heater

ABC Exchanger

1247 Locust

styrene Feed pump

XYZ Pumps 432 Broadway

styrene Feed heater

ABC Exchanger

1247 Locust

PlantName

Plant Mgr

ethylene

Jim Smith

styrene Bill Gunn

2nd OK but 3rd?


Database NormalizationPlantName

Eqpt name

Eqpt Mfgr

ethylene

Final cooler

ABC Exchanger

ethylene

Feed heater

ABC Exchanger

styrene Feed pump

XYZ Pumps

styrene Feed heater

ABC Exchanger

PlantName

Plant Mgr

Ethylene

Jim Smith

styrene Bill Gunn

Eqpt Mfgr

Mfgr Addr

ABC Exchanger

1247 Locust

XYZ Pumps

432 Broadway

Satisfies 3rd normal form


Database Normalization BCNF – Every determinant is a

candidate key

Fourth – Multi-valued dependencies

Fifth – Can recombine relations


Database Normalization

Domain Key (DK/NF) Provably free from anomalies But no one way to generate this form All constraints follow from domain

definitions and keys


Database Normalization

Domain Key (DK/NF)

“The key, the whole key, and nothing but the key”


Database Design Translating a model to the Database

Entities -> tables Establish primary & foreign keys Many-to-many relations ->Junction table Business rules -> triggers, constraints,

etc. Surrogate keys Security Typically done with a “CASE” tool


Database Design

HasEmployee

Auto #

One-to-one

1Auto

Emp #

1


Database Design

MakesMfgr

One-to-many

Mfgr #

1 NEquipment


Database Design

HasInvoice

One-to-many (w/ ID Dependency

Inv #

1 NLine Item

PK = inv#, item#


Database Design

Mfgr

Many-to-many

Mfgr_Eqpt

Equipment

M N

Mfg # Eqpt ID


Database Design

Referred byMember

Recursive

Member #

1

1


Database Design

Member

IS-A relationship (Subscriptions)

Print Online

Member#


Database Design Learning teams to implement

sample relations for above E-R relationships: 1 to 1 1 to many Many to many 1 to many w/ ID Dependency Recursive IS-A


SQL Two main language components

Data definition language (DDL)

Data manipulation language (DML)


SQL Data definition language (DDL)

Create, alter, drop, etc. Frequently implemented via various

CASE tools: Visio, Embarcadero, ERWin, etc.

But – also very useful for database administration


SQLCreate Statement

Create table patient(name varchar2(35) not null,age smallint,gender varchar2(1),account_number integer not null,primary key account_number)

<..additional constraints such as foreign keys, etc. ..>


SQLSelect (Projection)Select plantname

from equipment

Select (Restriction)Select *

from equipment

where eqpt_name = ‘feed heater’


SQLSelect (Selection + projection)

Select eqpt_namefrom equipmentwhere plantname = “styrene”

Sorting (Ordering)

Select *from manufacturersorder by eqpt_mfgr


SQL There are many built in functions Some are called aggregate

functions Count Max Avg Etc.

ExampleSelect max(age) from dependents


SQL

Joins (old syntax)

Select m.mfgr_addrfrom manufacturers m, equipment ewhere m.eqpt_mfgr = e.eqpt_mfgr

and e.plantname = ‘styrene’


SQL

Joins (new syntax)

Select m.mfgr_addrfrom manufacturers minner join equipment eOn e.name = m.namewhere e.plantname = ‘styrene’


SQL

Subqueries

Select m.mfg_addrfrom manufacturers mwhere eqpt_mfgr in(select e.eqpt_name from equipment e)


SQLInsertInsert into equipmentvalues(‘propylene’, ‘feed heater’,

‘ABC Exchanger’)

UpdateUpdate manufacturersSet address = ‘18 Front Road’Where mfgr_name = ‘ABC Exchanger’


SQL

Delete

Delete from equipmentWhere plant_name = ‘styrene’And eqpt_name = ‘feed cooler’

How many rows could this delete?


SQL Exercise

Create the tables in the design exercise

Create a few sample SQL selects, etc.

Functions of a Database Application

Page 238 Figure 10-1 © 2000 Prentice Hall


CRUD“the first function of a database

application is to CRUD views” Create Read Update Delete

Page 237


Format or Materialize views“the second function of a database

application; the appearance of the content”

Page 238


Other database functions Enforce constraints Provide for security and control Execute business logic

Page 238


View“A structured list of data items

(attributes) from the entities or semantic objects defined in the data model”

A view can be materialized or formatted as a form or report

Page 242


Recordset“the result of an SQL statement”

Page 243


CRUD actions on a viewRead

SELECT CUSTOMER.CustomerID, CUSTOMER.Name

FROM CUSTOMER, WORKWHERE CUSTOMER.CustomerID =

WORK.CustomerID

Page 243


CRUD actions on a viewCreate

INSERT INTO CUSTOMER(CUSTOMER.Name, CUSTOMER.City)

VALUES (NewCust.CUSTOMER.Name, NewCust.CUSTOMER.City)

Page 244


CRUD actions on a viewUpdate

INSERT INTO CUSTOMER(CUSTOMER.Name, CUSTOMER.City)

VALUES (NewCust.CUSTOMER.Name, NewCust.CUSTOMER.City)

Page 246

CRUD actions on a viewDelete

Cascading deletions depends on relationship cardinality



Form

“a screen display used for data entry and edit”

Forms should... reflect the view structure make data associations graphically

clear encourage appropriate action

Page 248


Forms in a GUI Environment Drop-down list Option buttons in groups Check boxes

Page 251

GUI controls



Report DesignReports should... reflect the structure of the

underlying view handle implied objects

Page 253


Enforcing Constraints Domain Uniqueness Relationship

Cardinality

1.1 and 1.N fragments orphans

Business Rule triggers

Page 256


Security Horizontal Vertical

Page 264


Control

System of menus

Transaction boundaries(Atomic unit of work)

Page 265

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