mysql - 如何连接三个 SQL 表以便我们可以从第三个表获取信息？

Question

考虑三个表 - 员工、地点和部门

Employee:
EmployeeID
Name
DeptID

Department:
DepartmentID
DeptName
LocID

Location:
LocationID 
LocationName

Employee.DeptID is a foreign key to Department.DepartmentID. 
Department.LocID is a foreign key to Location.LocationID

如何找到特定员工的 LocationName？例如。我们如何找到 EmployeeID 1234 的 LocationName？我们必须获取他/她的 DeptID，然后将其与 Department.DepartmentID 进行匹配，然后将该 Department.LocID 与 Location.LocationID 进行匹配，然后获取该 LocID 的 LocationName。谢谢

Answer 1

类似于以下内容:

select employee.name, employee.employeeID, location.name from employee join department on department.departmentID = employee.departmentID join location on location.locationID = department.locID

如果您想限制显示的员工，您可以添加一个 where 子句:

where employee.employeeID = 1234