>
> If product_id is actually an integer column, this function is
> technically broken: given a non-integer input, it will produce an error
> in the database.
>
I'm sorry, but I do not understand why would that code produce an error.
The value is properly escaped and formatted so there should be no error at
all. Is this based on some SQL setting? That SQL looks correct to me and I
do not see any syntax errors.
Also, silenced or not, if an error occurs on MySQL side then PHP has to
check for it one way or another or it will break with some other horrendous
error.