Question

我有两个SQL Server表...

MODULES        ENROLMENTS
GroupNo        StudentNo
Title          GroupNo
Tutor          CourseworkMark
DayNo          ExamMark
Time
Room
Semester

在Access中，我创建了一个基于另一个表的表单，该表保存了课程编号和名称的记录。对于每门课程，我希望创建一个关于该特定课程中模块的子表格。

在子窗体视图中，我希望拥有GroupNo，Title，Tutor，DayNo，Time，Room，Semester，CourseworkMark的平均值和ExamMark的平均值。

我构建了这个查询

SELECT tblEnrolments.GroupNo, Tutor, DayNo, Time, Room, Semester, 
       AVG(CourseworkMark) AS AvgCourseworkMark, AVG(ExamMark) AS AvgExamMark
FROM tblEnrolments INNER JOIN tblModules ON tblEnrolments.GroupNo = tblModules.GroupNo
GROUP BY tblEnrolments.GroupNo;

然而，我收到了错误

Msg 8120，Level 16，State 1，Line 1 专栏＆＃39; tblModules.Tutor＆＃39;在选择列表中无效，因为它不包含在聚合函数或GROUP BY子句中。

我跑的时候。如何获取查询中的Tutor，DayNo，Time，Room和Semester字段，因为它们不属于GROUP BY或AVG。谢谢

Answer 1

您必须按选择列表中的所有值进行分组，因此查询将如下所示：

SELECT tblEnrolments.GroupNo, Tutor, DayNo, Time, Room, Semester, 
       AVG(CourseworkMark) AS AvgCourseworkMark, AVG(ExamMark) AS AvgExamMark
FROM tblEnrolments INNER JOIN tblModules ON tblEnrolments.GroupNo = tblModules.GroupNo
GROUP BY tblEnrolments.GroupNo, Tutor, DayNo, Time, Room, Semester;

Answer 2

正如此错误所说

Msg 8120，Level 16，State 1，Line 1 Column＆＃39; tblModules.Tutor＆＃39;在选择列表中无效，因为它不包含在聚合函数或GROUP BY子句中。

并在评论中提及 @Gordon Linoff:

您需要在

中包含组中的所有非聚合列

SELECT tblEnrolments.GroupNo, 
                     Tutor, 
                     DayNo, 
                     Time, 
                     Room, 
                     Semester, 
                     AVG(CourseworkMark) AS AvgCourseworkMark, 
                     AVG(ExamMark) AS AvgExamMark
FROM tblEnrolments 
INNER JOIN tblModules ON tblEnrolments.GroupNo = tblModules.GroupNo
GROUP BY tblEnrolments.GroupNo ,Tutor, DayNo, Time, Room, Semester ;

SQL Server AVG函数错误

2 个答案: