using er/studio. 13- 2 modeling a relational database using er studio we will use er studio as the...

Using ER/Studio

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Modeling a Relational DatabaseUsing ER Studio

• We will use ER Studio as the modeling Tool to build ER diagrams.

• ER Studio Is a CASE tool providing a Repository (or System Catalog) of an organization’s databases

• Fully specified logical models in ER studio can be used to generate DDL – the code of the create tables statements

Getting to ER Studio Data Architect

• Enter ERS in the Search are of the start menu• Click on the ER Studio Data Architect 9.6 icon• Click on tools in the top menu and then select

options from the drop-down menu

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Set Options to Produce Crow’s-Foot Notation

Pick options from tools drop-downPick

logical

Choose Crow’s feet notation

Create a New Model

• Select File from the top menu and new from the drop down

• On the dialog box, ensure that Draw a new data model is checked and that relational is selected, then click OK

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Select an Entity to Add

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Entity Editor

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Name the entitythen make surethat the Attributestab is selectedand click the Addbutton to add attributes

Adding Attributes

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For each attributespecify its name,select a datatypefrom the listbox,select the columnwidth and checkwhether nulls areto be allowed for the attribute.

Check this box if the attribute is the primary key (or a

part of the PK)

Can specify derived attributes and check this box

Other Attribute PropertiesAdd Default value using the Default tab• Simply add the default

value: e.g. a system variable as shown or a ‘Y’ for a flag variable, etc.

Add check constraints using the rule/constraint tab• Note that a constraint name can be

specified• Check Constraint Value is the full

condition to be applied by the Check constraint– The @var begins the constraint

condition with the attribute name– & we just finish out the condition

Adding Relationships by Type

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identifying

Non-identifyingMandatory

Non- identifyingOptional

Relationship Types

• Identifying – Strong relationship child entity is a weak entity – Primary key of 1st entity becomes a foreign key and part of the

primary key of 2nd entity clicked.• Non-identifying Mandatory

– Weak relationship child entity is a strong entity– Primary key of 1st entity specified becomes a foreign key in 2nd

entity and foreign key attribute is not null• Non-Identifying Optional

– Weak relationship child entity is strong– Primary key of 1st entity specified becomes a foreign key in 2nd

entity, but the foreign key attribute can be null.

Editing Relationship Properties

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Auto add of FK

Identifying Relationship Specification

For identifying relationships,

Primary key of parent is

automatically added to

primary key of the child table

To complete this specification

Phone_No should be added to the primary

key of PATRON_PHONE

Creating a Sub-Class Hierarchy

• First create the Super-Class and sub-Class entities– Add at least the primary key to the super-class entity

• From the insert Drop-down, select sub-type cluster, then – pick either complete or incomplete – Click on the super-class entity– Control-click on the first subclass entity & continue

until all sub-class have been linked in(see next slide for menu option, following slide for

result.)

Choose complete (all super-type members must belong to a sub-type, or incomplete

Right click & pick edit subtype

cluster to get this Dialog box

Saving the Model

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Change to desired J drive space

Generating the Physical Model

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Physical Model for Oracle

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Generated SQL for Data Definition Language

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-- -- TABLE: ormCustomer --CREATE TABLE ormCustomer( custnumber NUMBER(10, 0) NOT NULL, name VARCHAR2(20), CONSTRAINT PK1 PRIMARY KEY (custnumber));-- -- TABLE: ormOrder --CREATE TABLE ormOrder( ordernumber NUMBER(10, 0) NOT NULL, orderdate DATE NOT NULL, total NUMBER(10, 0), custnumber NUMBER(10, 0) NOT NULL, CONSTRAINT PK2 PRIMARY KEY (ordernumber));-- -- TABLE: ormOrder --ALTER TABLE ormOrder ADD CONSTRAINT ReformCustomer31 FOREIGN KEY (custnumber) REFERENCES ormCustomer(custnumber);