자기 테이블을 참조하여 업데이트 update self table inner join

UPDATE g5_shop_item_last AS t1 

JOIN (SELECT it_id, it_explan FROM g5_shop_item_last) AS t2

USING (it_explan)

SET t1.it_mobile_explan = t2.it_explan;

----- by Using Set Based Approch

Update

[dbo].[EmployeeMaster]

set [EmpSalary]= am.AppraisedSalary

from

[dbo].[EmployeeMaster] em

inner join

[dbo].[AppraisedEmployee] am

on em.EmpId = am.EmpId