[email protected] skriver: > > Hi, > > I back with this question. Is this really correct because after > discussion with team i have now doubt. > > We have here parenthesis. Any expression in parenthesis should be > first calculated > Then this is not test > NOT NULL - > NULL only > Not ( NULL -> NULL) >
What do you mean with that last line "Not (NULL -> NULL)"? Think of "NULL" as "UNKNOWN" and add that if the value is forced to true/false NULL evaluates to false, the logic becomes rather intuitive: 1. "if NULL then 1 else 2 end" returns 2 2. "if not NULL then 1 else 2 end" returns 2 because "not NULL" is NULL and the expression degenerates to the same as example 1 above. Regards, Kjell
