Question

我有错误

1242 - 子查询返回超过1行

在

(SELECT COUNT(*) FROM attendance GROUP BY stu_ID   ) /(SELECT COUNT(if(`attstatus`='P', `attstatus`,NULL)) 
FROM attendance  GROUP BY stu_ID

我如何解决它，任何其他解决方案都可以显示attstatus='P'的百分比？

SELECT stu_ID,stu_name,

GROUP_CONCAT(if(class_no="lec_1", `attstatus`, NULL)) AS 'Lecturer 1',

GROUP_CONCAT(if(class_no="lec_2", `attstatus`, NULL)) AS 'Lecturer 2',

COUNT(if(`attstatus`='P', `attstatus`,NULL)) AS 'total p',

COUNT(if(`attstatus`='A', `attstatus`, NULL)) AS 'total a',

COUNT(*) as dayTotal,
(SELECT COUNT(*) FROM attendance GROUP BY stu_ID   ) /(SELECT COUNT(if(`attstatus`='P', `attstatus`,NULL)) FROM attendance  GROUP BY stu_ID) 



FROM attendance 

WHERE session_ID=1

GROUP BY stu_ID,stu_name;

Answer 1

尝试添加到您的sql： LIMIT 1
它只返回一行

SQL数据库＃1242 - 子查询返回多于1行

1 个答案: