1. The relational algebra is a procedural query language.

• Six fundamental operations:
  - select (unary)
  - project (unary)
  - rename (unary)
  - cartesian product (binary)
  - union (binary)
  - set-di erence (binary)
• Several other operations, de ned in terms of the fundamental operations:
  - set-intersection
  - natural join
  - division
  - assignment
• Operations produce a new relation as a result.