> I'm not sure I have enough knowledge to answer you so I think
> I'm replying to you personally but I think it would help you get
> your answer if you described what you would like to do with
> records that violate the unique(a,b) constraint.
If they violate, just ignore them. mysql have a insert ignore that
tries to insert and ignore any error and this is just the thing. I
could select and see if it is already there, but that seems a little
unessecery.