Third Normal Form and When to Break the Rules
Third normal form (3NF): no column should depend on another non-key column. If an employee table stores department and department_head, the head depends on the department, not on the employee. Move department details into their own table. A handy summary: every column depends on the key, the whole key, and nothing but the key.
Normalisation has a cost: more tables mean more joins to read the data. Large reporting systems sometimes denormalise on purpose, keeping a copy of data for speed, accepting that they must keep the copies in step. Start normalised; denormalise only for a measured reason.
Third normal form says every column depends on...
Look up the department head for employee 'Akua' using a join and print the head's name.
Finish the quick check (and any code exercise) to complete this lesson, or mark it done yourself.
Tip: use the left and right arrow keys to move between lessons.