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SimonMeduka avatar image
SimonMeduka asked

I need a check constraint - sql server

employee can never be her own manager. I need a constraint on the dbo.Employees to prevent this create dbo.Employees( EmpId INT primary key identity, MgrId INT , FullName NVARCHAR(50)) MgrId for general manager is NULL , REST MANAGER NUMBERS 1,2,3,4 etc ALTER TABLE dbo.Employees ADD CONSTRAINT CK_NULLforGeneralManager CHECK( 'can't figure it out')
sql-server-2012constraint
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Magnus Ahlkvist avatar image
Magnus Ahlkvist answered
How about this? ALTER TABLE dbo.Employees ADD CONSTRAINT CK_ManagerIsNotSelf CHECK (EmpId MgrId); I would also add a self referencing Foreign Key, to ensure that no Employee has a non existing employee as manager. ALTER TABLE dbo.Employees ADD CONSTRAINT FK_EmployeeManager FOREIGN KEY (MgrId) REFERENCES dbo.Employees(EmpId);
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Thank you so much! I am new to sql and looks so easy and simple.
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