Question

我需要提出sql问题，该问题会显示所有部门中至少有2个人。

SELECT department.name
FROM department
INNER JOIN employee
ON department.id = employee.department_id
GROUP BY employee.id
HAVING COUNT(employee.id) >= 2;

它没有向我显示任何有关此查询的内容

Answer 1

我认为您在错误的列上使用GROUP BY 如果您想计算每个部门的员工，那么您需要GROUP BY department.id。

SELECT department.id, department.name, COUNT(employee.id) AS total_employee
FROM department
INNER JOIN employee
ON department.id = employee.department_id
GROUP BY department.id, department.name
HAVING COUNT(employee.id) >= 2;

Answer 2

试试这个：

SELECT d.name
FROM department d
WHERE
    (SELECT COUNT(*) FROM employee e
    WHERE d.id = e.department_id) >= 2

这样，如果您想更改限制（而不是2，另一个值），您的查询就会有效。

如果您愿意，可以使用INNER JOIN，将来所有没有员工的部门都不能使用它。

找到至少有2名员工的部门

2 个答案: