WHERE子句中的SQL错误

Question

我有桌子

Department: id, name
Employee: id, departmentId, name, surname

departmentId是外键引用部门（id） 查询：

SELECT * FROM Employee WHERE Employee.departmentId = Department.id;

返回错误“where子句中的未知列Department.id”

我无法发出此错误。我该如何解决这个问题？

由于

Answer 1

您需要实际包含department表

SELECT * 
FROM Employee 
JOIN Department
   ON Employee.departmentId = Department.id;

这使用了ANSI标准的显式JOIN语法。你应该避免隐式连接。

Answer 2

那是因为你的Department表不在你的FROM子句中。包括它。

select *
from Employee, Department
where Employee.departmentId = Department.id

Answer 3

您未在from子句中包含部门....

SELECT * FROM Employee, Department WHERE Employee.departmentId = Department.id;