Name:

Quiz 10

Regarding Reading 10.

1. What is relational algebra?
2. What does the project operation do? Provide an example.
3. Consider the relations Surfers(id, name, board_id) and Boards(id, length, color), where Surfers.board_id is an FK pointing to Boards.id. Assuming there are some surfers without boards (dude! no board? bummer man!), describe the relation that results from the following algebra:
   
4. Translate the following relational calculus statement to english:
   

   { t.salary, t.hours_worked_per_week | STUDENTS(t) AND t.db_skill_rating > 5 }