Question

我有一张emp表，其中包含以下记录：

INSERT into emp(EmpId,Emp name, Manager)
Values(1,A,M1)
values(2,B,M1)
values(3,C,M2)
values(4,D,M3)

如何找到拥有最多员工人数的Manager？在这种情况下，输出应为M1。请帮忙。

Answer 1

select manager, count(*) as employees from emp
  group by manager
  order by count(*) desc

拿第一张唱片。根据您的SQL版本，您可以使用限制语句执行此操作。

Answer 2

SELECT
    Manager,
    count(Manager) AS 'Num of Emps'
FROM
    emp
GROUP BY
    Manager
ORDER BY
    'Num of Emps' DESC

第一条记录将是拥有最多员工的经理。此外，基于db提供程序，您可以将结果集限制为1，因此您只能获得最高记录。这是使用sql server的一个例子：

  SELECT
    TOP 1 Manager,
    count(Manager) AS 'Num of Emps'
FROM
    emp
GROUP BY
    Manager
ORDER BY
    'Num of Emps' DESC

Answer 3

在SQL Server中......

SELECT TOP 1 Manager
FROM  ( SELECT Manager,
               COUNT(Manager) as "ManagerCount"
        FROM emp
        GROUP BY Manager
        ORDER BY "ManagerCount" DESC )

Oracle有点不同......

SELECT Manager
FROM  ( SELECT Manager,
               COUNT(Manager) as "ManagerCount"
        FROM emp
        GROUP BY Manager
        ORDER BY "ManagerCount" DESC )
WHERE ROWNUM <= 1

Answer 4

在Postgresql中，创建模式测试：

create table Test.Employee (Emp_id numeric, manager_id numeric, Manager_name varchar(20));

insert into Test.Employee(emp_id, manager_id, manager_name ) values(1, 3, 'A'),  (2, 3, 'A'), (3, 3, 'A'), (4, 3, 'A'), (5, 11, 'B'), (6, 12, 'C'), (7, 11, 'B');

select manager_name from (select count(manager_id) as mcount, manager_name from test.employee group by manager_name order by mcount DESC) AS TEMP limit 1

Answer 5

如果你想要emp表中的行，请使用：

select * from emp
where empid in (select manager from 
    (select manager, count(*)
     from emp
     group by 1
     having count(*) = (select max(count) from (select manager, count(*) as count from emp group by 1) x)
    ) y );

如果大多数员工存在平局，这也会返回多行。

Answer 6

SELECT
    count(e.last_name) count,
    d.last_name
FROM
    employees e
LEFT OUTER JOIN employees d ON e.manager_id = d.employee_id
GROUP BY
    d.last_name
ORDER BY
    count DESC;

Answer 7

经过SQL Server 2017

的测试

Select TOP 1 City, Count(City) AS 'MAX_COUNT' FROM Customer Group By City Order By 'MAX_COUNT' DESC;

希望这个简单的查询会帮助很多人。

Answer 8

如果使用的是Oracle数据库，则只需使用stats_mode函数，该函数将返回出现次数最多的单个值。

sleep(30)

此功能非常易于使用，而不是编写多行sql查询。

编写SQL查询以获取列中值的最大值

8 个答案: