Querying empty fields

A pretty simple one I hope....I want to query a table and retrieve all EMPTY records (for the field margin_1 in this case). Here is the major part of the query so far..

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<cfquery name="clientDetails" datasource="#request.dsn#">
SELECT *
FROM client
WHERE team_name IN (SELECT team_name FROM round_#round_number# WHERE margin_1 = '1-9' )
</cfquery>
------------------------------------------

...which works, and outputs all users who selected the margin 1-9 (from a dropdown form box) but when I try and use WHERE margin_1 = '' to select all those who have not entered, it outputs nothing, even though there are several users that fit this criteria. Is there an easy way to select an empty field like this?

TIA
Mark

Have you tried using the 'null' character? That's just off the top of my head.

I sure have...and again, when I use
WHERE margin_1 <> null
I get results for all who have entered, BUT
both....
WHERE margin_1 = null
and
WHERE margin_1 <> not null
output zilch.

Try:

WHERE margin_1 IS NULL