Trying to write a query that can make the existing Postgres table that looks like first set below to give a result of the second set here:

```
ID | Month1  | Month2
A  |    2    |   3   --(qty)
B  |    4    |   5   --(qty)

```

**Result**

```
ID  | Month  | QTY
A   | Month1 | 2
A   | Month1 | 3
B   | Month1 | 4
B   | Month1 | 5 

```

The best idea is to use multiple unions but that would be very long. Is there a more efficient way to get around this?