>This update is very suspicious. First of all, why you're using LEFT JOIN? You want to update ParentTable no matter what?

I tried to simplify the SQL when I posted it in here. I also had to change the table names and fields. But, when I looked at it back, yes, the original SQL sent to me was using a LEFT JOIN. The original SQL contains four conditions. Three out of those four are from the LEFT JOIN table. One is from the main table. So, my guest is that is no record is found in the LEFT JOIN table, then the condition from the parent will be the only one left.

But, it may well be that it should have been INNER JOIN since the debut. I have to say I didn't pay attention to that part when I received it.