I have two columns, `confid1` and `confid2`. They both have the same data type.

I somehow need to bring `confid2` into `confid1`, but not concatenate them. Instead, insert it into a new line under `confid1`.

Original:

```
confid1     confid2
AACII1C1    AACII1C2

```

I have tried using UNION such as below:

```
(SELECT confid1 as ID1 FROM dyndomrun)
UNION
(SELECT confid2 as ID2 FROM dyndomrun)

```

It then returns the combination of `confid1` and `confid2` inside `confid1`, which is what I was looking for, as below:

```
confid1
AACII1C1
AACII1C2

```

Now, the problem is that one of the columns in another table links up with `confid1` and `confid2`, but it is all in a single column but multiple rows.

Right now, I have tried using the same `UNION` method, just adding the `pdbcode` into the code, such as below:

```
(SELECT confid1 as id1, conformer.pdbcode from dyndomrun, conformer where dyndomrun.confid1 = conformer.id)
UNION
(SELECT confid2 as id2, conformer.pdbcode from dyndomrun, conformer where dyndomrun.confid1 = conformer.id)

```

And it returns duplicate "pdbcode" values when it's not suppose to, as below:

```
confid1,    pdbcode
AACII1C1    2a4n
AACII1C2    2a4n

```

I want it to select and return a `pdbcode` column related to `confid1` and `confid2` such as below:

```
confid1,    pdbcode
AACII1C1    2a4n
AACII1C2    1b87

```