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Using ER/Studio. Modeling a Relational Database Using ER Studio. We will use ER Studio as the modeling Tool to build ER diagrams. ER Studio Supports the system catalog concept as well as recording information needed to support the data dictionary
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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 Supports the system catalog concept as well as recording information needed to support the data dictionary • Fully specified logical models in ER studio can be used to generate DDL • the code of the create tables statements
Set Options to Produce Crow’s-Foot Notation Pick logical Pick options from tools drop-down Choose Crow’s feet notation
Adding Relationships by Type identifying Non- identifying Optional Non-identifying Mandatory
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 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 entitys • 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 Change to desired H or J drive space
Generated SQL for Data Definition Language -- -- 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) ;