I remember a change in DBD::mysql a couple of years ago, where it suddenly became stricter about the type of data being used to fill in the placeholders - a number of scripts which previously worked, suddenly started to fail.

It was as though the DBD was interpreting "0" as a string rather than as a number.

As you have found, binding specific column/data types to each placeholder fixes the problem, and, as a bonus, adds a safety check to the data going to your DB.

Clint