I need to merge below Table 1 & Table 2 as indicated in "Merge".

[![enter image description here](https://i.stack.imgur.com/GgHR1.png)](https://i.stack.imgur.com/GgHR1.png)

The query I wrote below works; but it is TOO SLOW! Is there any simpler way which returns it faster?

```
SELECT T1.Loc, T2.SO, T2.PO, T1.Item
FROM Table1 T1

LEFT OUTER JOIN Table2 T2
ON ISNULL(T1.[SO2],T1.[SO1]) = T2.[SO]

```