sql查询创建新列并添加数据

Question

我想用他们经理的名字检索员工姓名。

例如：

Employee_Lastname：WARX
Employee_Firstname：CYNTHIA
MANAGER_NANE：SMITH

Warx Cythnia有经理，经理人身份证号码= 7369谁是史密斯约翰，因为史密斯有员工_ID = 7369

我想创建MANGER_NAME列并添加数据......

Answer 1

也许您只想投影记录的值，而不是在表格中添加新列？你只需加入这个，

SELECT  a.*,
        b.Employee_LastName AS MANAGER_LASTNAME
FROM    EmpTable a
        LEFT JOIN EmpTable b
            ON a.Manager_ID = b.Employee_ID

或

SELECT  a.Employee_LastName,
        a.Employee_FirstName,
        b.Employee_LastName AS MANAGER_LASTNAME
FROM    EmpTable a
        LEFT JOIN EmpTable b
            ON a.Manager_ID = b.Employee_ID

Answer 2

通常，您不会存储此类信息。但是你可以在查询时轻松获得它：

select
   t1.Employee_Lastname,
   t1.Employee_Firstname,
   t2.Employee_Lastname as manager_name
from [table] t1
       left join
     [table] t2
        on
           t1.manager_id = t2.employee_id