Oracle & Group By in Oracle

Question

执行代码：

SELECT sr2.CLASSIFICATIONID, COUNT (sr2.CLASSIFICATIONID) FROM SR sr2
GROUP BY (CLASSIFICATIONID)
ORDER BY COUNT (sr2.CLASSIFICATIONID) desc;

完美无缺。试图在没有任何列选择的情况下连接额外的表：

SELECT sr2.CLASSIFICATIONID, COUNT (sr2.CLASSIFICATIONID) FROM SR sr2
LEFT JOIN CLASSSTRUCTURE cl on cl.CLASSSTRUCTUREID=sr2.CLASSIFICATIONID -- joining
GROUP BY (CLASSIFICATIONID)
ORDER BY COUNT (sr2.CLASSIFICATIONID) desc;

1. 00000 -“列定义含糊不清”*原因： *行动:行处错误:第3栏: 11

我做错什么了？

Answer 1

哦，我只是想在小组里

GROUP BY (sr2.CLASSIFICATIONID)