Question

我有2个表，任务和员工。它们通过EmployeeNumber链接，HoursWorked是存储在赋值中的属性。我试过这个，我得到一个错误，说子查询返回超过1行。我做错了什么：

SELECT e.FirstName, e.LastName
FROM employee e
WHERE (
    SELECT a.HoursWorked
    FROM assignment a
    WHERE a.HoursWorked > 50);

Answer 1

看起来你正试图做这样的事情：

SELECT e.FirstName, e.LastName
FROM employee
JOIN assignment on employee.EmployeeNumber = assignment.EmployeeNumber
WHERE assignment.HoursWorked > 50;

Answer 2

SELECT e.FirstName, e.LastName FROM employee e WHERE e.EmployeeNumber IN ( SELECT EmployeeNumber FROM assignment a WHERE a.HoursWorked > 50);

MySQL帮助 - 员工在单个任务中工作超过50个小时？使用子查询？

2 个答案: