swa66 - 9:17 pm on Oct 14, 2012 (gmt 0)
To get it right: you want to see if there are lines in your table where in a given column there's a value that
a. starts with a number
b. equals a reference
Then why not turn it around: check in your php if the reference starts with a number (leaving SQL alone), and if it does, check in SQL for a line with the value of the reference.
BTW: you can use SELECTs in other SELECTs, but before you go there, try to explain the problem you're trying to solve first.