Project
- Output relation contains all rows, but only the specified columns.
- Duplicates are eliminated, because relations are sets.
R
| X |
Y |
Z |
| 1 | eee | 10 |
| 1 | eee | 20 |
| 2 | eee | 30 |
| 2 | fff | 40 |
| 3 | fff | 50 |
| 4 | fff | 60 |
| 4 | fff | 70 |
project(R, [X, Y])
| X |
Y |
| 1 | eee |
| 2 | eee |
| 2 | fff |
| 3 | fff |
| 4 | fff |
|