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First normal form (1NF) is the process of eliminating repeating data groups. This is done by representing data in the form of more than one entity. The remaining part of the normalization process analyzes entities and attributes in terms of functional dependence.
The rule states that for a primary key, there will be only one value for each non-key attribute.
Use the Order entity as an example. This is the Order entity before normalization:
Order
K Order number
K Customer code
Customer name
Customer phone number
Customer address
Customer postal code
Order date
Product code }
Product description } These attributes
Product size } can have up to
Product quantity } 4 sets of values.
Product price }
Order detail total }
Order total
Review the Order entity against the Order Entry Form, described under Step 1: Identifying Primary Entities.
This entity contains a repeating group of attributes: Product Code, Product Description, Product Size, Product Quantity, Product Price, and Order Detail Total.
Remove this repeating group of attributes.
Your Order entity now contains only these attributes:
Order
K Order number
K Customer code
Customer name
Customer phone number
Customer address
Customer postal code
Order date
Create a new entity and place the group of attributes you removed from the Order entity into this new entity:
Order Detail
K Order number
K Product code
Product description
Product size
Product quantity
Product price
Order detail total
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