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PONOT IN query... odd results
 

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    <p>I need a list of users in one database that are not listed as the <code>new_user_id</code> in another. There are 112,815 matching users in both databases; <code>user_id</code> is the key in all queries tables.</p> <p><br /> Query #1 works, and gives me 111,327 users who are NOT referenced as a new_user_Id. But it requires querying the same data twice.</p> <pre><code>-- 111,327 GSU users are NOT listed as a CSS new user -- 1,488 GSU users ARE listed as a new user in CSS -- select count(gup.user_id) from gsu.user_profile gup join (select cud.user_id, cud.new_user_id, cud.user_type_code from css.user_desc cud) cudsubq on gup.user_id = cudsubq.user_id where gup.user_id not in (select cud.new_user_id from css.user_desc cud where cud.new_user_id is not null); </code></pre> <p><br /> Query #2 would be perfect... and I'm actually surprised that it's syntactically accepted. But it gives me a result that makes no sense.</p> <pre><code>-- This gives me 1,505 users... I've checked, and they are not -- referenced as new_user_ids in CSS, but I don't know why the ones -- that were excluded were excluded. -- -- Where are the missing 109,822, and whatexcluded them? -- select count(gup.user_id) from gsu.user_profile gup join (select cud.user_id, cud.new_user_id, cud.user_type_code from css.user_desc cud) cudsubq on gup.user_id = cudsubq.user_id where gup.user_id not in (cudsubq.new_user_id); </code></pre> <p><br /> What exactly is the where clause in the second query doing, and why is it excluding 109,822 records from the results?</p> <p><br /> <strong>Note</strong> The above query is a simplification of what I'm really after. There are other/better ways to do the above queries... they're just representative of the part of the query that's giving me problems.</p>
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    1. USJames King
    1. USJames King
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    1. CODo both tables have nulls in the columns that is used for joining? I guess yes, from the results you have.
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      1. USypercubeᵀᴹ
    2. CONo, they are joined on the primary key.
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    3. CO@ypercube I think the problem is the use of the NOT IN, cudsubq.new_user_id can be NULL. Read my answer to the question.
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      1. USRoger
 

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