Given the table Employees(EmpID, Name, Dept, DeptPhone) with dependencies:…

To satisfy Third Normal Form (3NF), the single table must be decomposed into Employees(EmpID, Name, Dept) and Departments(Dept, DeptPhone). The original table violates 3NF because it contains a transitive functional dependency (EmpID → Dept → DeptPhone) , where the non-prime attribute DeptPhone depends on EmpID via another non-prime attribute, Dept. Under 3NF rules, a non-prime attribute can only be determined by a super key; since Dept is not a super key, keeping all fields in one table creates redundancy and anomalies.

To resolve this violation, the transitive dependency is isolated by splitting the attributes into two target relations. The first table, Employees, retains the candidate key EmpID along with its direct attributes (Name and Dept). The second table, Departments, extracts the violating dependency so that Dept becomes its primary key to cleanly map DeptPhone. This specific decomposition ensures a lossless join and preserves all functional dependencies, allowing the original schema to be perfectly reconstructed using Dept as a foreign key connection.