为什么这个表达式在 MS-ACCESS SQL 视图中不起作用

Question

SELECT
    Pname,
    Dname,
    COUNT(WO.Essn),
    SUM(WO.Hours)
FROM
    PROJECT AS P,
    WORKS_ON AS WO,
    DEPARTMENT AS D
WHERE
    P.Dnum = D.Dnumber
    AND P.Pnumber = WO.Pno 
GROUP_BY Pno
HAVING
    COUNT(WO.Essn) > 1;

我得到

in query expression . (Error 3075)

此代码有误。我应该改变什么

Answer 1

你group by的说法不正确：

SELECT
    Pname,
    Dname,
    COUNT(WO.Essn),
    SUM(WO.Hours)
FROM
    PROJECT AS P,
    WORKS_ON AS WO,
    DEPARTMENT AS D
WHERE
    P.Dnum = D.Dnumber
    AND P.Pnumber = WO.Pno
GROUP BY  
    Pname,
    Dname
HAVING
    COUNT(WO.Essn) > 1;

Answer 2

学习使用正确的 JOIN 语法。在 MS Access 中，这看起来像：

SELECT P.Pname, D.Dname,
       COUNT(WO.Essn), SUM(WO.Hours)
FROM (PROJECT AS P INNER JOIN
      WORKS_ON AS WO
      ON P.Pnumber = WO.Pno 
     ) INNER JOIN
     DEPARTMENT AS D
     ON P.Dnum = D.Dnumber
GROUP_BY P.Pname, D.Dname
HAVING COUNT(WO.Essn) > 1;

为什么这个表达式在 MS-ACCESS SQL 视图中不起作用

Why does not this expression work in MS-ACCESS SQL View

sql

database

ms-access

database-design