In SQL, you'd write DateField IS NULL. In Perl, that NULL value is represented by undef, so you'd write not defined($DateField).
Jeff japhy Pinyan,
P.L., P.M., P.O.D, X.S.:
Perl,
regex,
and perlhacker How can we ever be the sold short or the cheated, we who for every service have long ago been overpaid? ~~ Meister Eckhart