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Editorial Team
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Asked: 2026-05-17T17:40:57+00:00

I have a litte problem with a mysql query. I use 5 tables: user_has_data

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I have a litte problem with a mysql query.

I use 5 tables:

user_has_data (uid, dataid); users (uid, uname); user_in_group(uid, groupid, data); groups(groupid, data, packageid); packages(packageid, name)

all ids are PK. I want to build a sql query that finds a user, which belongs to a specified dataid, by its uname and checks if the user is in a group (relation in table user_in_group) belonging to a specified package (a group is assigned to one package). if so data from users, package and group should be fetched, otherwise only the user data should be fetched. Therefore I use left joins, so I can also get the users with no group:

SELECT `uac`.`uid`, `u`.`uid`, `uig`.`groupid`, `ag`.`packageid` 
FROM `user_has_data` AS `uac` 
INNER JOIN `users` AS `u` ON u.uid = uac.uid 
LEFT JOIN `user_in_group` AS `uig` ON uig.uid = uac.uid 
LEFT JOIN `groups` AS `ag` ON (ag.groupid = uig.groupid) AND (ag.packageid = 2) 
WHERE (uac.dataid = '3') AND (u.uname LIKE 'test%')
GROUP BY `u`.`uid`

Unfortunately I get wrong results: I get groups that have a different packageid than stated in the join, if the user has another group assigned to him with a different packageid.

probably this is because the first left join has no restrictions to packageid and the second is a left join and so it has no restrictions on the result (packageid is NULL for all results, but should have values). If I change the second left join to a ordinary join, the group problem would be fixed but the query cant find users without group any more.

Any ideas how to fix this or even possible?
thanks in advance!

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1 Answer

  1. Editorial Team

    Are you saying that you are actually seeing the value ag.packageid = 2 in your query results?

    If not, I think you might try something like:

    SELECT `uac`.`uid`, `u`.`uid`, `g`.`groupid`, `g`.`packageid` 
FROM `user_has_data` AS `uac` 
INNER JOIN `users` AS `u` ON u.uid = uac.uid 
LEFT JOIN (`user_in_group` AS `uig` 
  INNER JOIN `groups` AS `ag` ON (ag.groupid = uig.groupid) AND (ag.packageid = 2) )
 AS `g` ON uac.uid = g.uid
WHERE (uac.dataid = '3') AND (u.uname LIKE 'test%')
GROUP BY `u`.`uid`
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