Question

I have table Employee. I need to update manager id using excel sheet (to get value from excel I have written below query)

Employee

Emp_ID  Emp_Code Name  ManagerID
1       1111     xyz    2
2       2222     abc    3
3       3333     mno    2

I have written query like this

UPDATE Employee  SET ManagerID = Emp_ID   from Employee  inner join  Employee AS MGR 
on Employee.emp_id=MGR.emp_id    WHERE  emp_code='1111'

but its not updating the correct value

Answer 1

Based on what you’ve told us, you don’t need a self join at all, i.e. you can simply update an employee’s manager id directly

UPDATE Employee  
    SET ManagerID = 2 
    WHERE  emp_code='1111'

etc

However, if you mean that you need to perform the update given only the emp_code of the employee and the emp_code of the manager (i.e. without the Manager’s PK), then you can use a subquery (uncorrelated), e.g.

UPDATE Employee  
    SET ManagerID = (SELECT manager.Emp_Id 
                       FROM Employee manager 
                       WHERE manager.emp_code = '2222') -- Manager's emp_code
    WHERE  emp_code='1111' -- Employee to update's emp_code

If you then later need to add a query showing the employee and his / her manager (and assuming that the ultimate boss doesn’t have a manager), you can do the self join like so:

SELECT emp.emp_code as EmployeeCode, emp.name as EmployeeName, 
       mgr.emp_code as ManagerEmpCode, mgr.name as ManagerName
FROM Employee emp 
   LEFT OUTER JOIN Employee mgr 
   ON emp.ManagerId = mgr.Emp_Id