OK, so the vulnerable URL that I'm attacking has only one column and the only way to retrieve data from that column is to generate an error. The column normally accepts an int value so any string value returns an error. However, when I try to cast an int to a string as to return an error like: union select convert(varchar,zip) from address I don't get an error. How can I generate one? Additionally, conversion to type text only gives the error "Operand type clash: text is incompatible with int".