First Normal Form

The basic development the analyst should make to such a record structure is to design the record structure so in which all records in the file are of fixed length.

A repeating group, which is, the reoccurrence of a data item or group of data items within a record, is really another relation. This is erased from the record and treated as an further record structure or relation.


                                             First Normal Form – Employee Record

As mentioned above the first normal form is carried out through removing the repeating group. In this case we erased the Annual salary earned items and involved them in a new file or relation known as Annual Salary earned record. Employee number is since the primary key in the employee record. The combination of employee number and MMYY is the primary key in the annual salary earned record.We therefore form two record structures of fixed length: Employee record consisting of Employee no., employee name, employee details (grade, department code, date of joining, exit date and exit code), bank details (bank name, bank code, employees A/C no address,)

Annual salary earned record consisting of – employee no., month & year (MMYY) and net paid.

In the attributes mentioned above that the first Normal form must not hold repeated groups. Here the frequent groups are products. When the Invoice Attribute is in 1st Normal Form, the tables would be given below:

Invoice_Master    Invoice_Item
Invoice_code       Invoice_No
Inv_date                item_code
Order_code            ord_qty
Order_qty              ucst
Cust_code             Ord_value            
Cust_name            description
Address
Invoice_value

The attributes which are indicated as bold indicate primary key.