此SQL查詢有什么問題

Question

我需要找出此SQL有什么不好的地方：

SELECT DepartmentName, COUNT(*) 
FROM employee,department 
WHERE employee.DepartmentID = department.DepartmentID 
GROUP BY DepartmentName
WHERE COUNT(*)>1

我認為COUNT(*)的問題是因為它返回所有行的計數。 因此，我認為沒有where語句的sql屬性將如何。 幫幫我，我不太擅長SQL。

Answer 1

你必須使用具有 cluase，而不是展示在聲明的結尾：

SELECT DepartmentName, COUNT(*) 
FROM employee,department 
WHERE employee.DepartmentID = department.DepartmentID 
GROUP BY DepartmentName
having COUNT(*)>1

Answer 2

SELECT DepartmentName, COUNT(*) AS count
FROM employee,department 
WHERE employee.DepartmentID = department.DepartmentID 
GROUP BY DepartmentName
HAVING count>1;