DBI202 - Review 1

The ER Diagram uses three principle element types:

• Entity sets, Attributes and Constraints

• Entity sets, Attributes and Relationships

• Attributes, Constraints and Relationships

• Entity sets, Constraints and Relationships

Schema-altering commands are known as _________ commands.

• Data Definition Language

• Data Manpulation Language

• Data Controlling Language

• None of the others

The DBMS (Database Management System) is expected to:

• Allow users to create new databases and specify their schemas

• Allow users to query the data

• Support the storage of very large amounts of data

• All of the others

The ER model means that:

• enable detailed descriptions of data query processing

• replace relational design

• enable low level descriptions of data be close to

• be close to a perception of the data

Consider a relation with schema R(A, B, C, D) and FD's A -> B, A -> C, C -> D. Which of the following is the {A}+ ?

• {A}

• {A,B,C,D}

• {A,B,C}

• {A,B}

When we define an attribute A as PRIMARY KEY of relation R, then __________

• We may define more primary keys on the relation R

• None of the others

• There are no two tuples that have the same values on the A component

• Tuples must be null on the A component

Which of the followings was the first ever used for data model?

• Tree based model

• Graph based model

• Relational model

• File system

Which of the followings is false about weak entity set?

• Every many - one relationship from a weak entity set need be supporting

• Every many - one relationship from a weak entity set need be supporting

• A weak entity set has one or more relationships to other (supporting) entity set

• Do not contruct a relation for any supporting relationship

Which of the followings is not applied while converting UML diagrams to relations?

• None of the others

• For each aggregation or composition, create a relation

• For each class, create a relation

• For each association, create a relation

Which of following statement is correct?

• Every relation must have only one primary key

• Primary key has only one attribute

• Primary key has only one attribute

• Super key is a special primary key