Select rows with multiple distinct column value combinations

Question

I have a table with 3 columns: id, val1 and val2.

For each distinct value of val2 I want to select all rows for which multiple distinct values of val1 exist.

Example:

| id | val1 | val2 |
|------------------|
| 1  | A1   |  a2  |
| 2  | A1   |  a2  |
| 3  | A1   |  b2  |
| 4  | B1   |  b2  |
| 5  | A1   |  c2  |
| 6  | A1   |  c2  |
| 7  | A1   |  c2  |
| 8  | A1   |  d2  |
| 9  | C1   |  d2  |
| 10 | A1   |  d2  |

Desired result:

| id | val1 | val2 |
|------------------|
| 3  | A1   |  b2  |
| 4  | B1   |  b2  |
| 8  | A1   |  d2  |
| 9  | C1   |  d2  |
| 10 | A1   |  d2  |

I did not manage to come up with any query which allows me to do this, maybe someone else has an idea on how to solve this.

Answer 1

You could use a having clause to search for val2 with more than one distinct value of val1. For example:

select  yt.*
from    YourTable yt
join    (
        select  val2
        from    YourTable
        group by
                val2
        having  count(distinct val1) > 1
        ) as filter
on      yt.val2 = filter.val2