http://www.perlmonks.org?node_id=192444


in reply to Re: Re^2: DBD::mysql Unusual Behavior
in thread DBD::mysql Unusual Behavior

The NULL fields actually consume an astounding extra bit per record, so while they're convenient and all, if the difference between "empty" and NULL is trivial, it's often easier to just throw in an empty value.

Since the column in question was not allowed to be NULL, you're required to check before INSERTion.