CSIS 326 midterm Poole

Generalization Hierarchy

A collection of entites arranged to represent a similarity in attributes. The Subtypes have attributes of the supertype.

Foreign Key

A primary key of one table that appears as an attribute in another table and acts to provide a logical relationship between the two tables.

Self referencing entity type

A relationship involving the same entity type. Represents an association between members of the same set.

Weak entity.

Borrows all or some of its primary key from another entity type.

Cardinality

Constraint on the number of objects that participate in a relationship. ex 1 to 1, 1 to M, N to M.

Completeness

Every entity of a supertype must be an entity in one of the subtypes of the generalization hierarchy.

Underlined Attribute

Primary key of entity in a ERD

Attributes

Properties of entity types and relationships.

This is a Left outer Join.

SELECT FacNo, FacFirstName, FacLastName, FacSalary, StdNo FROM Faculty LEFT JOIN Student ON Student.StdNo = Faculty.FacNo What is included in this select statement?

This is a right outer join

SELECT FacNo, FacFirstName, FacLastName, FacSalary, StdNo FROM Faculty RIGHT JOIN Student ON Student.StdNo = Faculty.FacNo What is included in this select statement?

This is a Full outer join.

SELECT column_name(s) FROM table1 FULL OUTER JOIN table2 ON table1.column_name = table2.column_name; What is included in this select statement?

This includes a Type I nested query to implement a difference operation.

SELECT eventrequest.eventno, custname, contact, dateauth FROM eventrequest, customer WHERE eventrequest.custno = customer.custno AND status = "Approved" AND eventno NOT IN ( SELECT eventno FROM eventplan WHERE workdate BETWEEN '10/1/2007' AND '10/31/2007') What is included in this select statement?

This is a inner join.

SQL> SELECT ID, NAME, AMOUNT, DATE FROM CUSTOMERS INNER JOIN ORDERS ON CUSTOMERS.ID = ORDERS.CUSTOMER_ID; What is included in this select statement?

Type II subqueries.

Used for "difference" problems: What data in the outer query does NOT exist in the subquery?

Identifying relationship

a relationship where another entity provides part or all of the primary key for the entity.

Assosiative entity type

a weak type entity that depends on two or more entities for its primary key.

Disjoint

the subtypes of the generalization hierarchy do not have any entites in common.

Entites

things of interest, has attributes and relationships