mysql - WHERE 子句中的 SQL 错误

Question

我有桌子

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

departmentId 是引用 Department(id) 的外键查询：

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

返回错误“where 子句中的未知列 Department.id”

我不能放置这个错误。我该如何解决？

谢谢

Answer 1

您实际上需要包含department表格

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

这使用JOINANSI 标准的显式语法。您应该避免使用隐式连接。

Answer 2

那是因为您的Department表不在 FROM 子句中。包括它。

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

Answer 3

你没有在你的 from 子句中包括 Department....

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