ORA-00979：不是GROUP BY表达式 [英] ORA-00979: not a GROUP BY expression

问题描述

我想展示学生们工作的所有不同公司。

I am trying show all the different companies for which students work. However only companies where more than four students are employed should be displayed.

这是我到目前为止：

SELECT EMPLOYER, COUNT (STUDENT_ID)
FROM STUDENT
GROUP BY STUDENT_ID
HAVING COUNT (STUDENT_ID) >4;

我一直收到此消息：

ERROR at line 1: 
ORA-00979: not a GROUP BY expression

b $ b

我不明白。我也尝试过这个早期：

I don't get it. I also tried this earlier:

SELECT STUDENT.EMPLOYER, COUNT (STUDENT.STUDENT_ID)
FROM STUDENT
GROUP BY STUDENT.STUDENT_ID
HAVING COUNT (STUDENT.STUDENT_ID) >4;

但似乎没有任何效果。任何帮助是赞赏。

but nothing seems to work. Any help is appreciated. I am on SQL*Plus if that helps.

推荐答案

尝试：

SELECT EMPLOYER, COUNT (STUDENT_ID)
FROM STUDENT
GROUP BY EMPLOYER
HAVING COUNT (STUDENT_ID) >4;

- 这将返回所有有超过4名学生的雇主的列表。

- this will return a list of all employers with more than 4 students.

在分组或包括聚合字段时，select语句应仅包括组中聚合或包含的字段$ c> clause - 在您现有的选择中，您在select子句中包括 EMPLOYER ，但不能按其分组或聚合。

When grouping or including aggregated fields, your select statement should only include fields that are either aggregated or included in the group by clause - in your existing select, you are including EMPLOYER in your select clause, but not grouping by it or aggregating it.

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