Data Science Database_Quiz1

Each table in a relational database must have a primary key.

• True
• False

The one­ to­ many (1:M) relationship is easily implemented in the relational model by putting the foreign key of the “1” side in the table of the “many” side as a primary key.

• True
• False

In the relational model,  _____ are important because they are used to ensure that each row in a table is uniquely identifiable.

• Relations
• Keys
• Indexes
• Logical structures

A                is the primary key of one table that has been placed into another table to create a common attribute.

• superkey
• composite primary key
• candidate key
• foreign key

The CUSTOMER table’s primary key is CUS_CODE. The CUSTOMER primary key column has no null entries, and all entries are unique. This is an example of  ________integrity.

• entity
• referential
•  relational
• null

 ________ are especially useful when you are trying to determine what values in related tables cause referential integrity problems.

• Inner joins
• Outer joins
• Equijoins
• Theta joins

The entity relationship model (ERM) is dependent on the database type.

• True
• False

A composite identifier is a primary key composed of more than one attribute

• True
• False

Relationships between entities always operate in one direction.

• True
• False

A weak relationship exists if the primary key of the related entity contains at least one primary key component of the parent entity.

• True
• False