2021-09-09
- Homework:
R:
| A | B | C | D |
|---|---|---|---|
| 2 | 5 | 5 | 6 |
| 2 | 4 | 5 | 3 |
| 9 | 10 | 7 | 9 |
| 10 | 14 | 3 | 1 |
S:
| A | B | X | Y |
|---|---|---|---|
| 2 | 5 | 12 | 13 |
| 9 | 10 | 7 | 8 |
| 10 | 4 | 6 | 9 |
- R X S
- R Join S
- R $\bowtie_{(y<c \text{ and } R.B=/= S.B)}$ S
R:
| A | B | C | D |
|---|---|---|---|
| 2 | 5 | 5 | 6 |
| 2 | 4 | 5 | 3 |
| 9 | 10 | 7 | 9 |
| 10 | 14 | 3 | 1 |
S:
| A | B | X | Y |
|---|---|---|---|
| 2 | 5 | 12 | 13 |
| 9 | 10 | 7 | 8 |
| 10 | 4 | 6 | 9 |