Customer Database Table Example

Let us take a look at an example table that contains customer data:

Because this is a basic order table, you can easily see that the table contains the

1. customer ID, (CustID)
2. name, (Name)
3. city, (City)
4. ordered item ID, (Item_ID) and
5. description. (Description)

For each item, the quantity and extended total are included.
You can quickly see that many elements are duplicated, making the table redundant to read through and requiring additional storage space. The way the data is currently displayed in the table, you would need to add two new columns to include the additional address information and the individual cost per item before this becomes a useful set of information. Normalization, in simple terms, says that there will be one and only one reference to information in a given database, and that tables that use that information will use a pointer (primary key to be introduced later). For example, customer ID (CustID) and item ID above. We will normalize this table in the next lesson, so click on the Next» link located at the top or bottom of this page.