I have the following table where col2 might have the same or different values and col1 is the key field. How can I select only the rows where col2 is different for col1 (like I have in the second table)?
| col1 | col2 |
| 1 | B |
| 1 | B |
| 1 | B |
| 2 | C |
| 3 | A |
| 3 | D |
| 3 | D |
| 3 | H |
| 4 | E |
| 5 | F |
| 5 | G |
| 5 | I |
| col1 | col2 |
| 3 | A |
| 3 | D |
| 3 | H |
| 5 | F |
| 5 | G |
| 5 | I |