不唯一 table/alias (42000)

Question

我收到错误 ERROR 1066 (42000)：不唯一 table/alias：'STUDENT_TBL'

select STUDENT,DATE,MARK from Assessments inner join STUDENT_TBL on Assessments,ID_STUDENT=STUDENT_TBL,STD_ID inner join Visit_log,ID_STUDENT=STUDENT_TBL,STD_ID where STUDENT_TBL,STD_ID IN (select ID_STUDENT FROM Assessments group by ID_STUDENT having avg(MARK)>3.7);

如何解决？

Answer 1

如果您使用架构和表名，则必须像这样用点分隔它们

select STUDENT, Assessments .`DATE`,MARK from Assessments
inner join STUDENT_TBL on Assessments.ID_STUDENT=STUDENT_TBL.STD_ID
inner join Visit_log.ID_STUDENT=STUDENT_TBL.STD_ID
where STUDENT_TBL.STD_ID IN (select ID_STUDENT FROM Assessments group by ID_STUDENT having avg(MARK)>3.7);

Answer 2

您应该使用 '.' 而不是 ',' 来访问 Table_Name.column_name。

select STUDENT,DATE,MARK 
from Assessments AS Assessments 
inner join STUDENT_TBL AS STUDENT_TBL on Assessments.ID_STUDENT=STUDENT_TBL.STD_ID 
inner join Visit_log AS Visit_log on Visit_log.ID_STUDENT=STUDENT_TBL.STD_ID 
where STUDENT_TBL.STD_ID IN (select ID_STUDENT FROM Assessments 
                             group by ID_STUDENT having avg(MARK)>3.7

也使用像 Assessments.ID_STUDENT 这样的别名，而 selecting select 子句中的列，如果它们出现在多个 table

中

不唯一 table/alias (42000)

Not unique table/alias (42000)

mysql

alias

mysql-error-1066