SQL query doesn't work when using UNION?
-
22-09-2019 - |
Question
Here is the snapshot of the query that doesn't work since I added the Union.
SELECT fin05_usager.idUsager,
(SELECT sum(nombreReputation) as nombreReputation
FROM (SELECT SUM(nombreReputationGagner) as nombreReputation
FROM fin05_usager_reputation
WHERE fin05_usager_reputation.idUsager = fin05_usager.idUsager
GROUP BY fin05_usager_reputation.idUsager
UNION
SELECT SUM(cc_badge.valeurEnReputation) as nombreReputation
FROM cc_badge, fin05_usager_badge
WHERE fin05_usager_badge.idBadge = cc_badge.idBadge
AND fin05_usager_badge.idUsager = fin05_usager.idUsager) as repuUnion
) as repu
FROM fin05_usager
WHERE fin05_usager.idUsager = 6
The error is : #1054 - Unknown column 'fin05_usager.idUsager' in 'where clause'
If I remove the fin05_usager.idUsager and use directly '6' it does work.
If I remove the union and use only one of the 2 select it works (what ever if I take the FROM fin05_usager_reputation or the other one FROM cc_badge, fin05_usager_badge.
Why when using the UNION the error about finding the idUsager appear and without the union no error is found?
Schema simplified:
fin05_usager: idUsager int(8)
fin05_usager_reputation : idUsager int(8), nombreReputationGagner int(4)
cc_badge : idBadge int(4), valeurEnReputation int(4)
fin05_usager_badge : idUsager int(8), idBadge int(4)
Note:
I cannot do the subquery directly in the query. I have to use it inside a subquery in the select because in real, the query is very big and already contain Group, etc.
Solution 2
Alright,
The only way I found for the moment without doing a Group By in the main query (since in the real situation I can't because it does contain already a Group By clause) is to do it in 2 and to merge it with the code... not exaclty what I would like but it works at least:
SELECT fin05_usager.idUsager,
(SELECT sum(nombreReputationGagner) as nombreReputation1
FROM fin05_usager_reputation
WHERE fin05_usager_reputation.idUsager = fin05_usager.idUsager
group by fin05_usager_reputation.idUsager) as nombreReputation1
,
(SELECT sum(cc_badge.valeurEnReputation) as nombreReputation2
FROM cc_badge, fin05_usager_badge
WHERE fin05_usager_badge.idBadge = cc_badge.idBadge
AND fin05_usager_badge.idUsager = fin05_usager.idUsager) as nombreReputation2
FROM
fin05_usager
where fin05_usager.idUsager = 6
In the code I sum the nombreReputation1 and nombreReputation2.
OTHER TIPS
When you mention that removing the UNION causes things to work, I'm betting that you're removing this specifically:
UNION
SELECT SUM(cc_badge.valeurEnReputation) as nombreReputation
FROM cc_badge, fin05_usager_badge
WHERE fin05_usager_badge.idBadge = cc_badge.idBadge
AND fin05_usager_badge.idUsager = fin05_usager.idUsager
This piece contains the refernce to fin05_usager.idusager
that the mysql error is referring to. Subquery access is only allowed to one level - both ways. Nevermind that you really shouldn't be doing a SELECT within the SELECT clause. Here's how I reinterpret your query:
SELECT fu.idUsager,
a.nombreReputation + b.nombreReputation AS repuunion
FROM fin05_usager fu
JOIN (SELECT fur.idusager,
SUM(fur.nombreReputationGagner) as nombreReputation
FROM fin05_usager_reputation fur
WHERE fur.idUsager = fin05_usager.idUsager
GROUP BY fur.idUsager) a ON a.idusager = fu.idusager
JOIN (SELECT fub.idUsager,
SUM(ccb.valeurEnReputation) as nombreReputation
FROM cc_badge ccb
JOIN fin05_usager_badge fub ON fub.idbadge = ccb.idbadge
GROUP BY fub.idUsager) b ON b.idusager = fu.idusager
WHERE fu.idUsager = 6