Correction Re: [Not So] Simple Query Issues (Improved Grammer)
Correction Re: [Not So] Simple Query Issues (Improved Grammer)
- Subject: Correction Re: [Not So] Simple Query Issues (Improved Grammer)
- From: Jonathan Rochkind <email@hidden>
- Date: Mon, 31 Mar 2003 14:59:52 -0600
Oops, to be clear, the query I wrote as:
SELECT A.item1, A.item2, A.item3
FROM A LEFT OUTER JOIN B ON A.item1 = B.item1
WHERE B.item1 = null
should of course really be:
SELECT A.item1, A.item2, A.item3
FROM A LEFT OUTER JOIN B ON A.item1 = B.item1
WHERE B.item1 is null
You can't use = with null and have it mean anything useful. 'is null' instead.
--Jonathan
At 09:24 AM 3/31/2003 -1000, Art Isbell wrote:
On Sunday, March 30, 2003, at 05:22 PM, I wrote:
On Sunday, March 30, 2003, at 08:54 AM, Brian Allen wrote:
I have not been able to determine how to do some basic queries within
WebObjects that can be easily done using SQL.
For example, two tables A and B with a number of columns.
SELECT A.item1, A.item2, A.item3 FROM A,B WHERE A.item1 <> B.item1
The query should return all of the records within table A that did not have
any matches between the A.item1s and the B.item1s.
The above query doesn't specify any relationship between
entities A and B.
Upon further consideration, I suppose the above query does
specify a relationship between entities A and B. However, the
relationship is based upon the inequality of attributes whereas EOF's
relationships are based on the equality of attributes. I don't know of a
way to define a relationship in EOF based on the inequality of
attributes. Suggestions?
Aloha,
Art
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