Your first example only uses one variable in the place.

Your second example uses three placeholders, but you don't want categories.id_cat to be compared as a string.

Placeholders only work for constant values, not for column references. You will need to use string interpolation for that.

In reply to Re: Avoid embedding variables in SQL - Dancer App by Corion
in thread Avoid embedding variables in SQL - Dancer App by GertMT

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