Sql 子查询有子句错误，我缺少什么？

为什么我会犯这个错误

 SELECT        unitCode
        FROM            Enrolment
        WHERE        count(studentID) >
         (SELECT        AVG(Students) AS avgstudents
        FROM            (SELECT        COUNT(*) AS Students
       FROM            Enrolment AS Enrolment_1
        GROUP BY unitCode) AS a))

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看起来最后有一个额外的帕伦。我不太懂SQL，所以我不能说是否有其他错误，或者paren是否是一个问题。

在where子句中，我们不能使用聚合函数。可以在HAVING子句中使用countstudentID函数

 SELECT        unitCode
        FROM            Enrolment
        WHERE        count(studentID) >
         (SELECT        AVG(Students) AS avgstudents
        FROM            (SELECT        COUNT(*) AS Students
       FROM            Enrolment AS Enrolment_1
        GROUP BY unitCode) AS a))

检查这个样本

 SELECT        unitCode
        FROM            Enrolment
        WHERE        count(studentID) >
         (SELECT        AVG(Students) AS avgstudents
        FROM            (SELECT        COUNT(*) AS Students
       FROM            Enrolment AS Enrolment_1
        GROUP BY unitCode) AS a))

SELECT department, SUM(sales) as "Total sales"
FROM order_details
GROUP BY department
HAVING SUM(sales) > 1000;

大卫，看看这个

 SELECT        unitCode
        FROM            Enrolment
        WHERE        count(studentID) >
         (SELECT        AVG(Students) AS avgstudents
        FROM            (SELECT        COUNT(*) AS Students
       FROM            Enrolment AS Enrolment_1
        GROUP BY unitCode) AS a))

select count(*),unicode from Enrolement 
    having count(StudentID) > (select avg(Students) ad avgstudents,unitCode
    from table_Name where Enrolement = "some of ur condtion"
    group by unitCode) 

需要更改格式化语法的查询。。相应地检查您的查询业务。

尝试以下操作：

 SELECT        unitCode
        FROM            Enrolment
        WHERE        count(studentID) >
         (SELECT        AVG(Students) AS avgstudents
        FROM            (SELECT        COUNT(*) AS Students
       FROM            Enrolment AS Enrolment_1
        GROUP BY unitCode) AS a))

select unitCode
from Enrolment
group by unitCode
having count(*) > (select avg(c.c) from (select count(*) as c from Enrolment group by unitCode) c);

适当尊重：

 SELECT        unitCode
        FROM            Enrolment
        WHERE        count(studentID) >
         (SELECT        AVG(Students) AS avgstudents
        FROM            (SELECT        COUNT(*) AS Students
       FROM            Enrolment AS Enrolment_1
        GROUP BY unitCode) AS a))

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我该把声明放在哪里？在子查询中？在where cluse only的位置，您只需更改该值，而不是在子查询中，选择count，city FROM employee GROUP BY city have count=SELECT maxcount*FROM employee GROUP BY city；你能更新一下你的代码吗？这样我就能正确地看到它了？im使用手机查看此网站，只需告知您需要选择unicode或需要使用聚合函数（如总和、计数）选择任何其他数据。因为如果使用having子句，我们无法在select中没有任何聚合func值的情况下进行选择。能否更改第一个问题中的确切代码以实现having子句？能否将WHERE COUNTSDUNTID>更改为having语句以使其工作？我只想显示值高于AVGSDUNTS的unitCodes子查询