更新时间:2023-01-19 23:39:08
很简单 -
SELECT empname,
empid,
(SELECT COUNT(profileid)
FROM profile
WHERE profile.empid = employee.empid)
AS number_of_profiles
FROM员工;
使用如下表连接更简单:
SELECT e.empname,e.empid,COUNT(p.profileid)AS number_of_profiles
FROM employee e LEFT JOIN配置文件p ON e.empid = p .empid
GROUP BY e.empname,e.empid;