you cannot assign an alias like that, using the dreaded, evil "select star"
first of all, you should stop using that
secondly, you have to use table aliases like this --
, <font color='"Blue"'>maincat</font>.*
, <font color='"blue"'>subcat</font>.*
but even then, your troubles are not over, because both of your tables (maincat and subcat) have the same columns, so you should really assign column aliases to them as well
do a search for threads within this forum for "join same table twice" and i'm sure you will find numerous examples
now ~that's~ funny!!
it means "both of them"