There are different types of database design. We will begin with the database design from existing data. It is a common type of design. Let’s think about a small company. They have employees, products, sales etc. and all their data recorded into spreadsheets. One day, the owner of the company decided to transfer all the data into computer. It is safer and useful. At this point, the first step is analysing spreadsheets and other data tables. Then, extract data. Finally, design the database using normalization principles. This is an example to design from existing data.
The other type of database design is new system development. At this type, there is nothing at the beginning. The first step is analysing system requirements. Then, data model is created from the requirements. After that, transform data model into database design. Briefly, there are four basic steps:
Analysing System Requirements -> Create Data Model -> Data Model Transformation-> Database Design
Another type of design is database redesign and it the last type that we will write about. This type is used for migration old databases to newer databases or integration of databases.
Database1 —-migration—> Database Design2
Database1+Database2 ——integration——–> Database Design3
You need to know database design implementation using SQL before you can understand database redesign. There are lots of source can easily found on the internet.
To sum up, there are three types of database design. Database design from existing data, New system development and Database redesign.