此SQL查询有什么问题

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

我认为COUNT(*)的问题是因为它返回所有行的计数。 因此，我认为没有where语句的sql属性将如何。 帮帮我，我不太擅长SQL。

Answer 1

你必须使用具有 cluase，而不是展示在声明的结尾：

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;