False queries and optimizer

Is there any way to slip fake queries past the online5 optimizer? E.g., select * from foo where field1=42 works fine, uses the index on field1, while select * from foo where 1=0 or field1=42 has the optimzer doing a sequential scan on all of foo... (As for "why do I care", I had a simple piece of code to build a query, e.g. [psuedocode]: q = "select * from foo where 1=0" if (thing1) q = q + " or field1 = " + value1 if (thing2) q = q + " or field2 = " + value2 ... etc. Without the leading "1=0" it gets painful to decide if each 'if' should start with "or" or not. The same problem arises with 'and', so it's not as simple as switching to a bunch of unions, and also in this specific case it would be ugly to use unions, since all of that combinations is further conjoined with some other logic (e.g., "select * from foo where field9=42 and ..otherstuff.. and (1=0 or....). But it did fail in the above simple case, and also with "and 1=1".) Does the optimizer not recognize simple optimizations? Ought it not "guess" that this has probability 0? -- Andrew Burt aburt@du.edu "But if he was dying he wouldn't bother to carve "Aaaaargh", he'd just say it."