In the definition, it says minimal key is a minimal set of attributes needed to identify the table. Does the "minimal" part mean "minimal number of attributes" or "cannot be eliminated"?
For example:
- For a relation
R(A, B, C, D, E, F)
, the closure ofA
,BC
, andDEF
are all{A, B, C, D, E, F}
.
Are they all minimal keys? Or is only A
the minimal key?
Best Answer
They are all minimal keys.
Minimal means there is no proper subset with the same property.