> Sorry, I don't understand what you mean by this. I meant that the current test case would result in true in both ordering - so in this sense, it's not the best testcase:
SELECT (istrue IMPLIES isnul) IS NULL FROM booltbl4; SELECT istrue IMPLIES (isnul IS NULL) FROM booltbl4; are both true If you change it to SELECT isfalse IMPLIES isnul IS NULL FROM booltbl4; Then those would have different results, making it a better testcase.
