relational algebra

The attribute which is the primary key should have its values never?

• changed

• independent

• Dependent

• None of the above

The referential integrity constraint of a relational database can be specified with the help of?

• Primary Key

• Secondary Key

• Foreign Key

• None of the above

Minimal Superkeys are also called?

• Primary Key

• Candidate Key

• Foreign key

• None of the above

Set of one or more attributes taken collectively to uniquely identify a record is called?

• 
  primary key

• candidate key

• foreign key

• super key

The number of attributes in a relation is called its?

• Cardinality

• Degree

• Strength

• None of the above

Which of the following factors indicates that a table is not well-structured?  

• primary key consists of more than one attribute

• referential intergrity is violated when attempting to enter data

• it contains multiple foreign kays

• All the above