> -- If I have interpreted SQL92 correctly UNKNOWN IS TRUE should return
> FALSE, and UNKNOWN IS NOT TRUE is equivalent to NOT (UNKNOWN IS TRUE) ==>
> TRUE. Is this correct?
No, I do not think it is valid to say "should return true|false"
I think they should return UNKNOWN. Only when it comes to evaluating the
"... WHERE UNKNOWN;" can you translate it to "... WHERE FALSE;", or in the
output function.
My interpretation would be:
UNKNOWN IS TRUE --> FALSE
UNKNOWN IS NOT TRUE --> FALSE
NOT (UNKNOWN IS TRUE) --> FALSE
Andreas
