Sql 显示用子查询连接两个表的列
因此,我似乎不知道如何显示与子查询连接的列Sql 显示用子查询连接两个表的列,sql,Sql,因此,我似乎不知道如何显示与子查询连接的列 SELECT INSTRUCTOR, count(case when grade = 'A' then 1 end) totalA FROM Grade_report AS gr, Section WHERE Section.SECTION_ID=gr.SECTION_ID AND (gr.GRADE='A') GROUP by INSTRUCTOR ORDER by totalA DESC 我还想选择SECTION_ID并显示它。但当我把它放在se
SELECT INSTRUCTOR, count(case when grade = 'A' then 1 end) totalA
FROM Grade_report AS gr, Section
WHERE Section.SECTION_ID=gr.SECTION_ID
AND (gr.GRADE='A')
GROUP by INSTRUCTOR ORDER by totalA DESC
我还想选择SECTION_ID并显示它。但当我把它放在select行时,它会显示一个模棱两可的列名“SECTION_ID”
非常感谢您的帮助。这个怎么样
SELECT INSTRUCTOR, gr.SECTION_ID, count(case when grade = 'A' then 1 end) totalA
FROM Grade_report AS gr, Section
WHERE Section.SECTION_ID=gr.SECTION_ID
AND (gr.GRADE='A')
GROUP by INSTRUCTOR, gr.SECTION_ID
ORDER by totalA DESC
由于两个表中的列名相同,因此必须指定表名(或别名)以避免歧义(这就是错误试图告诉您的)。您还必须将新列包括在GROUPBY子句中。选择gr.SECTION\u ID或SECTION.SECTION\u ID;编译器不知道选择哪一个。使用
gr.SECTION\u ID
?有两种,gr.SECTION\u ID
和SECTION.SECTION\u ID
,您必须从中选择一种。