>>No, this is an OK way although I would rather use MERGE command instead. Also, if the inner select always returns 2 rows and you want it to return 2 rows, use UNION ALL instead of UNION.
>
>In this case, UNION ALL didn't change anything.
>
>Thanks for the reference for the merge.

I know, but you're doing an extra work using UNION as UNION also does distinct. Since in your case you never need a distinct result, you need to use UNION ALL.