That check constraint won't prevent rows in tEmployeesStatus from being deleted/updated if there's a matching row in the child table. A foreign key will (or will cascade the delete/update if required)
The check constraint doesn't give the optimiser extra information about the relationship, a foreign key will.
Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability