relational algebra

Which of the following is used to denote the selection operation in relational algebra?

• Pi (Greek)
  

• b) Sigma (Greek)

• c) Lambda (Greek)

• d) Omega (Greek)

The ___operation, denoted by −, allows us to find tuples that are in one relation but are not in another.

• a) Union
  

• b) Set-difference

• c) Difference

• d) Intersection

Which is a join condition contains an equality operator:

• a) Equijoins
  

• b) Cartesian

• c) Natural

• d) Left

The select,project,rename operations are

• Binary operators

• ternary operators

• unary operators

• none of the above

Using the select operation, you can select ___ that satisfy certain criteria

• 1. Tuples

• 1. Attributes

• 1. Operators

• 1. None

Relational tables can include ___ primary keys.

• 1. Only 1

• 1. Only 2

• 1. More than 2

• 1. As many as you want