Using LIMIT 1 in MySQL

Question

When is it appropriate to add LIMIT 1 at the end of the query in MySQL. I normally add it in DELETE but I\'ve seen it being used with INSERT a and even UPDATE. Is it an overkill

Answer 1

Well, if you use EXPLAIN you'll see that it speeds things up, as once it's found one result, it stops.

It's also a failsafe – if you know your insert of update should only ever affect one row, by specifying it, you are guaranteeing that it won't ever go wrong and mess up multiple rows.