SQL update using values from the same record
===

In the following statement, will `f1` always get the value that `f2` used to have? Or will `f2` sometimes get updated first and `f1` winds up with `NULL`? I am under the impression that the new values are not available within the statement, that `f2` has the old value while processing the record, but I can't find an authoritative place that says this.

    UPDATE x
    SET
        x.f1 = x.f2,
        x.f2 = NULL

