On Mon, 13 Oct 2003, Robert Partyka wrote:
> why such condition:
> foofield not like '%bar%'
>
> where foofield is varchar
>
> returns false (or rather even ignore row) on record where foofield is
> null
Actually, it probably returns unknown(NULL) on such records.
NULL LIKE '%bar%' is unknown, so
NULL NOT LIKE '%bar%' is also unknown.
This is because NULL isn't the same as empty string, nor is it the absence
of a value, but it's an unknown value.
