A table is in second normal form (2NF) if and only if it is in 1NF and every nonkey attribute is fully dependent on the primary key.
An attribute is fully dependent on the primary key if it is on the right side of an FD for which the left side is either the primary key itself or something that can be derived from the primary key using the transitivity of FDs.
A table is in the Second normal form if all its non-key fields are fully dependent on the whole key.
This means that each field in a table, must depend upon the entire key.
Those that do not depend upon the combination key, are moved to another table on whose key they depend on.
Structures which do not contain combination keys are automatically in the second normal form.
The Second normalization makes sure that each non-key attribute depends on a keuy attribute or on a composite key.
Non-key attributes that do not meet this condition are split into simpler entities.
The creation of the Second table offers several benefits. These are:
Sales items can be added without being tagged to a specific salesperson.
If the item changes we need to change only the item file.
If a salesperson leaves the department, it would have no direct effect on the status of the items sold.