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POMySQL, multiple table update and strange result
primarykey
Id
4956561
data
AcceptedAnswerId
0
AnswerCount
3
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CommentCount
0
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CreationDate
2011-02-10T11:33:15.097
FavoriteCount
1
LastActivityDate
2012-05-03T21:09:00.007
LastEditDate
2012-05-03T21:09:00.007
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1209430
OwnerUserId
231456
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PostTypeId
1
Score
1
ViewCount
470
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text
Body
I've got two tables : TEST1 : <pre><code>id int, value int, parentId int </code></pre> and TEST2: <pre><code>id int, value int, parentId int </code></pre> In TEST1, I've got following records: <pre><code> id value parentId 1 0 1 2 0 1 3 0 1 </code></pre> in TEST2, I've got: <pre><code>id value parentId 1 0 1 </code></pre> I want to update the two tables in one update using multiple table feature. The goal is to add +1 value to each records of TEST1 and +1 value to the record in TEST2 where the parentId is similar to TEST1. My query is : <pre><code>UPDATE TEST1 t1 LEFT OUTER JOIN TEST2 t2 ON t1.parentId=t2.parentId SET t1.value = t1.value + 1, t2.value = t2.value + 1; </code></pre> After that, I do a select to check that values of TEST1 have been updated : <pre><code>SELECT * FROM TEST1; </code></pre> It gives me : <pre><code>id value parentId 1 1 1 2 1 1 3 1 1 </code></pre> I check TEST2 : <pre><code>SELECT * FROM TEST2; </code></pre> It gives me : <pre><code>id value parentId 1 1 1 </code></pre> What I find strange is that the record of TEST2 has a value of 1. I would expect 3 because the update of TEST1 is on 3 records and so the update of TEST2 should occurs three times on the same record. Why I obtain 1 instead of 3 ? and What is the correct query to obtain 3 ? EDIT: I've also tried : <pre><code>SET @var=1; UPDATE TEST1 t1 LEFT OUTER JOIN TEST2 t2 ON t1.parentId=t2.parentId SET t1.value = t1.value + 1, t2.value = (@var:= @var + 1); </code></pre> After this query, t2.value is equal to 2 ! And not 4 as I would expect.
Tags
<mysql><sql><sql-update><multiple-tables>
Title
MySQL, multiple table update and strange result
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1. USJuan Mellado
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1. USJerome Cance
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1. This table or related slice is empty.

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