On Wed, Jan 15, 2003 at 17:23:09 -0000, [EMAIL PROTECTED] wrote: > > How do nulls work? > ================== > There is one very important rule when dealing with nulls. The result of > any operation or comparison, when applied to a null is null. The only > exception is testing if a value is null.
I suggest rephrasing this to make it clear you need to use is null to do this and that = null won't do what you expect. > If you try to perform an operation on nulls, again the result is always > null. So the results of all of the following are null: The above isn't true (i.e. null op something isn't ALWAYS null). For example: bruno=> select 't'::boolean or null; ?column? ---------- t (1 row) ---------------------------(end of broadcast)--------------------------- TIP 4: Don't 'kill -9' the postmaster
