我的 SQL 查询不工作 [重复]

Question

可能重复：
Is there a way to make this SQL more efficient?

考虑下表：

• department:

  deptid (type: INT)
  deptname (type: TEXT)
  hours (type: INT)
  active (type: BIT)
  

• employee:

  empid (type: INT)
  empname (type: TEXT)
  deptid (type: INT)
  designation (type: TEXT)
  salary (type: INT)
  

编写查询以返回属于员工人数为 4 人或更多的部门的员工的列 empname 和 deptname。记录应按empname 的字母顺序返回。

我的解决方案如下。

SELECT e.empname,d.deptname
FROM employee e,department d
WHERE e.deptid=d.deptid
      AND d.deptid
         IN
(
SELECT deptid
FROM employee
GROUP BY deptid
HAVING COUNT(*)>=4
)
ORDER BY e.empname;

Answer 1

您的问题的答案可以在this link找到。

SELECT employee.empname, department.deptname
FROM employee
INNER JOIN department ON employee.deptid = department.deptid
WHERE employee.deptid IN 
(
  SELECT employee.deptid
  FROM employee
  GROUP BY employee.deptid
  HAVING COUNT(employee.deptid) >= 4
)
ORDER BY employee.empname ASC;

编辑：如果您希望我解释此解决方案中的任何内容，请随时提出。 :)