1242 - Subquery returns more than 1 row MySQL

I have a simple dummy sql with my dummy head:(

select if(`linktype`="group", (select contactgroups.grname 
    开发者_开发百科                           from contactgroups, groupmembers 
                                   on contactgroups.id=groupmembers.id),2) 
from groupmembers

this should list only the groups name but I can't see what I've done wrong again:( Any help, please?

Another try:

SELECT contactgroups.grname
FROM contactgroups, groupmembers
WHERE contactgroups.id = groupmembers.id

works well gives 2 group names back. So this is why the error message. But if I select from groupmembers it should match with the groupmembers.group_id with the contactgroups.id

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if must return a scalar value. Never tested it but try to substitute contactgroups.grname with group_concat(contactgroups.grname)

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Not sure why you are including the groupMembers table in the subquery, but how about this alternative:

SELECT IF(`linktype`="group", (SELECT contactgroups.grname 
                               FROM contactgroups 
                               WHERE contactgroups.id=groupmembers.id),2) 
FROM groupmembers

or better yet, get rid of the subquery altogether as it is not needed

SELECT IF(`linktype`="group", contactgroups.grname,2) 
FROM groupmembers
LEFT JOIN contactgroups ON (contactgroups.id = groupmembers.id)

Also, I have a sneaking suspicion that your contactgroups table has multiple entries for one or more of your groupmembers table entries. You might want to confirm that too.

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The nested select

(select contactgroups.grname on contactgroups.id=groupmembers.id)

seems to return more than 1 row, You could use LIMIT to restrict this. Or if it's not expected, check your data.