Mysql 选择员工人数最多的部门

我有两个表

EMP（id，name，DEPT\u id）

和

DEPT（id，name）

。我需要找到员工人数最多的部门。请帮忙

试试这个查询

SELECT a.name,Max(a.NumEmp) AS maxEmpCount FROM ( SELECT d.name,COUNT(*) AS NumEmp FROM EMP e INNER JOIN DEPT d  ON e.DEPT_id = d.id GROUP BY e.DEPT_id ) AS a GROUP BY a.name

Select Id, Name from Dept
Where Id = (Select Top(1) DeptId from Emp 
            Group By DeptId
            order by Count(DeptId) desc)

---

您可以尝试此查询

SELECT a.name,Max(a.NumEmp) AS maxEmpCount FROM ( SELECT d.name,COUNT(*) AS NumEmp FROM EMP e INNER JOIN DEPT d  ON e.DEPT_id = d.id GROUP BY e.DEPT_id ) AS a GROUP BY a.name

Select Id, Name from Dept
Where Id = (Select Top(1) DeptId from Emp 
            Group By DeptId
            order by Count(DeptId) desc)

---

只是比其他两个解决方案更详细一点，但它会完成工作…请随意调整以方便您

select countbydept.*
from
(
  -- from EMP table, let's count number of records per dept
  -- and then sort it by count (highest to lowest)
  -- and take just the first value. We just care about the highest
  -- count
  select dept_id, count(*) as counter
  from emp
  group by dept_id
  order by counter desc
  limit 1
) as maxcount

inner join

(
  -- let's repeat the exercise, but this time let's join
  -- EMP and DEPT tables to get a full list of dept and 
  -- employe count
  select
    dept.id,
    dept.`name`,
    count(*) as numberofemployees
  from dept
  inner join emp on emp.dept_id = dept.id
  group by dept.id, dept.`name`
) countbydept 

-- combine the two queries's results by matching the employee count
on countbydept.numberofemployees = maxcount.counter

---

示例：

您可以创建视图来查找它

CREATE VIEW TEMP AS SELECT COUNT(EMP.id) AS A, DEPT.name AS B 
FROM EMP JOIN DEPT ON EMP.DEPT_id=DEPT.id GROUP BY DEPT.id;

SELECT MAX(A) FROM TEMP;

现在，EMP（id，name，DEPT_id）和DEPT（id，name）这两个表已经给出。现在，我以如下方式在表中插入一些条目：

SELECT COUNT(*) AS NO_OF_EMPLOYEES,
       DEPARTMENT.DEPT_NAME
  FROM EMP, DEPARTMENT
 WHERE EMP.DEPT_ID=DEPARTMENT.DEPT_ID
 GROUP BY EMP.DEPT_ID
 ORDER BY NO_OF_EMPLOYEES;

此查询生成以下内容：

NO_OF_EMPLOYEES DEPT_NAME
3               Research
3               Finance
4               Sales
4               Product

现在，给出正确结果的查询：

SELECT COUNT(*) AS MAX_NO_OF_EMPLOYEES,
       DEPARTMENT.DEPT_NAME
  FROM EMP, DEPARTMENT
 WHERE EMP.DEPT_ID=DEPARTMENT.DEPT_ID
 GROUP BY EMP.DEPT_ID
HAVING MAX_NO_OF_EMPLOYEES=(
    SELECT COUNT(*) AS NO_OF_EMPLOYEES
      FROM EMP
     GROUP BY DEPT_ID
     ORDER BY NO_OF_EMPLOYEES DESC
     LIMIT 1
);

它将产生：

MAX_NO_OF_EMPLOYEES    DEPT_NAME
4                      Sales
4                      Product  

---

这个问题可以用多种方法解决

• 使用子查询

  SELECT name FROM dept WHERE id IN (SELECT dept_id FROM emp HAVING COUNT(dept_id) IN (SELECT MAX(COUNT(dept_id)) FROM emp) GROUP BY dept_id)
  

  SELECT name FROM emp e INNER JOIN dept d ON e. dept_id = d. id HAVING COUNT(e.dept_id) IN (SELECT MAX(COUNT(dept_id)) from emp) group by dept_id)
  

• 使用Join

  SELECT name FROM dept WHERE id IN (SELECT dept_id FROM emp HAVING COUNT(dept_id) IN (SELECT MAX(COUNT(dept_id)) FROM emp) GROUP BY dept_id)
  

  SELECT name FROM emp e INNER JOIN dept d ON e. dept_id = d. id HAVING COUNT(e.dept_id) IN (SELECT MAX(COUNT(dept_id)) from emp) group by dept_id)
  

---

这将给出员工人数最多的部门的部门名称

Select DEPT_NAME from department where DEPT_ID = (select DEPT_ID from (Select DEPT_ID, count(DEPT_ID) from Employee group by DEPT_ID order by count(DEPT_ID) desc) where rownum = 1);

---

您可以使用以下语句解决此问题：

with deps as
 (select dep.department_name as dep_name, count(emp.employee_id) as cnt
    from departments dep
   inner join employees emp
      on emp.department_id = dep.department_id
   group by dep.department_name)
select deps.dep_name,cnt from deps 
where cnt=(select max(cnt) from deps)

或

或

这些解决方案适用于像Oracle这样的数据库，我们没有

top（1）

或

limit 1

select Top 1 d.DNAME,count(e.ename) as counts from emp e,dept d where d.DEPTNO=e.DEPTNO
group by d.DNAME
order by counts desc

或

---

若你们只有emp表，那个么下面的查询将帮助你们得到一个结果-

select a.* from (select deptno, dense_rank() over(order by count(*) desc ) as rank  from dbo.emp group by deptno) a  where a.rank =1

---

如果有多个部门具有最大数量。我应该如何修改此查询。请格式化您的代码：）谢谢彭。我正要编辑。但是，我不得不去某个地方。现在，我回来了，你的编辑让我很高兴。你能详细说明答案而不是仅仅给出答案吗？见：