> > Thus it could be, that NULL in "where column = NULL" is not defined > > to have a special meaning according to SQL92. > > The way I interpret Celko's interpretation of SQL92, that specific > construct has a meaning; it evaluates to UNKNOWN, thus not to TRUE, Imho the text refers to a content of a particular column of one particular row. where table1.col1 = table2.col1 the content of table2.col1 is null --> comparison evaluates to UNKNOWN. It does not state whether NULL is a valid constant expression. Andreas ---------------------------(end of broadcast)--------------------------- TIP 2: you can get off all lists at once with the unregister command (send "unregister YourEmailAddressHere" to [EMAIL PROTECTED])