Just to add my two cents. . .

$numberofrows will be '0E0' in the event that no rows were updated, but the query was sucessful. It will be '0' if the query failed (i.e. bad SQL).

'0E0' is a value that evaluates to true in a boolean context, but acts as the number 0 in a numeric context. I always thought that was quite interesting.

Updated: Typos fixed.