Re: Differentiate Between Zero-Length String and NULL Column Values

On Tue, Jan 30, 2007 at 04:32:22PM +1100, Phillip Smith wrote:
> The second row (401600) is what I'm interested in for this particular
> problem. The problem is when I try and add a WHERE clause:
> SELECT * FROM tmpstk WHERE ean = '';
> SELECT * FROM tmpstk WHERE TRIM(ean) = '';
> SELECT * FROM tmpstk WHERE ean = NULL;
> None of the above queries return any rows.

Checking for equality against NULL won't work unless you have
transform_null_equals set, which you shouldn't. Use IS NULL instead:

SELECT * FROM tmpstk WHERE ean IS NULL;

--
Michael Fuhr