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sqlsql-serverdatabase-normalization

Normalizing data

I need to update the managerid field with the related employeeid.

CREATE TABLE Employee(
EmployeeID Int Primary Key Identity,
Name Varchar(50),
ManagerID INT default 0,
ManagerName Varchar(50) default ''
)
INSERT INTO Employee(Name,ManagerName) VALUES('Dilbert','Boss')
INSERT INTO Employee(Name,ManagerName) VALUES('Boss','Dogbert')
INSERT INTO Employee(Name) VALUES('Dogbert')
SELECT * FROM Employee
GO
-- This is the update stmt I need help with
UPDATE Employee 
SET ManagerID=EmpID
WHERE ManagerName = Name
Solution

  • You can join on the Employee table to find a manager's id:

    UPDATE emp
SET ManagerID = boss.EmployeeID
FROM Employee emp
INNER JOIN Employee boss
    ON boss.Name = emp.ManagerName

    Be aware that storing both the manager's name and the manager's id in an employee row violates 3rd Normal Form.