The first design principle ~ Reducing redundant data by dividing info into subject-based tables
The database of Products and Suppliers we used in our lab exercise divides info into subject-based tables. For example, if we want to select the fields to be included in the report. From the Product table, we can choose Product Category, Product Name, Selling Price, Quantity on Hand and Reorder Level. From the Supplier table, we can choose Company Name which is the name of the supplier for that product. Then, we group the report according to Product Category and sort the data in each product category by Product Name afterward. Therefore, these subject-based tables help to reduce redundant data.
The second design principle ~ Helps supporting & ensuring the accuracy & integrity of the info
Since the database is not mixed information of two different objects, like orders and customers in a single table, that helps supporting and ensuring the accuracy and integrity of those information. As a result, any decisions are made will not contain incorrect information.
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For the second design principle - "helps supporting and ensuring the accuracy and integrity of the info" - relational databases also restrict the data type of each field, so that only valid data can be entered in each record (e.g. non-numeric data can be entered in a numeric field).
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