The requirements of various paradigms
The first paradigm: every field is atomic and every item in the table is inseparable.
The second normal form: first satisfy the first normal form, and the second normal form needs to be satisfied, and the non-primary attribute is completely determined by the primary key. That is, a primary key only determines a row.
The third normal form: satisfy the second normal form, but also satisfy that there is no transitive dependency, to put it simply, the non-primary attributes in one table should not appear in another table.
