COMP3311 Final Exam 20T3

Question 11 (9 marks)

Assume that we have a collection of relations as follows:

R(a,b,c)   S(d,e)   T(a,d,f)

Write relational algebra equivalents of the following SQL statements. You may write multiple steps, with one RA operation in each step. Use the notation which has implicit projections and renaming by writing attribute names on the left-hand side of the "assignment", e.g.

 Tmp1(a,b) = Sel[c=5]R

rather than

Tmp = Rename[R→Tmp](Proj[a,b](Sel[c=5]R))

The final step should produce a relation called Res.

Exercises:

```
select * from R;
```
```
select a,b from R where c < 0;
```

select a,d from R join S on (b = e) where c < 0;

select b,c,e,f from R natural join T natural join S;

Instructions:

Type your answers to this question into a file called q11.txt
Submit via: give cs3311 exam_q11 q11.txt or Webcms3