• you are most definitely can use AND/OR condition in the ON clause 🙂

    I have been using them forever...

    also you can use an AND in MATCHED stmt.

    Like so:

    MERGE T

    Using S

    ON

    t.col = s.col

    WHEN MATCHED AND <otherTcol = otherScol condition> THEN

    Update blah blah blah

    but very cautiously

    that part of MERGE is not always working as desired/expected.