加入＆amp;在Oracle中分组

Question

执行代码：

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

一切都很完美。 尝试在没有任何列选择的情况下加入额外的表：

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 - “列模糊定义” *原因：
   *行动： 行错误：3列：11

我做错了什么？

Answer 1

哦，我只需要GROUP BY中的id

GROUP BY (sr2.CLASSIFICATIONID)