sql查詢創建新列並添加數據

Question

我想用他們的經理名稱檢索員工姓名。

例如：

Employee_Lastname：WARX
Employee_Firstname：CYNTHIA
MANAGER_NANE：SMITH

Warx Cythnia與經理標識= 7369 THA經理誰是史密斯約翰因爲史密斯擁有的Employee_ID = 7369

我想創建MANGER_NAME列並添加數據...

Answer 1

也許你只想要t o投射記錄的價值，而不是在表格右側添加新的專欄？你只需要加入這個，

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

通常情況下，你會不會保存這些信息。但在查詢時您可以輕鬆獲得：

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