Designing and implementing a database can be a complicated and time-consuming process. There are six distinct steps in the database design life cycle, and it is important for database designers to pay careful attention to each step along the way. It is much easier to design a database properly from the start than to go back and fix a flawed design after the fact.
During this initial phase of the database life cycle, the database developer and other members of the team learn about the requirements, including what the database is intended to do and what problems it needs to solve. Database designers talk to managers, end users and others about the database and take notes that will help them build the tables, queries and reports they need.
The next phase is the design phase. During this phase the database developer sketches out the tables that will make up the database and develops the relationships between the tables. For instance, an employee database might contain one table for demographic information, another for salary information and a third for benefits. Each of these tables is linked by a common element, such as a Social Security number or employee ID.
During the logical design phase, the database developer identifies the primary key of the database, as well as the data types used for each field. In the case of an employee database, the primary key could be the employee Social Security number or employer ID.
When the physical design phase begins, the database developer actually begins coding the database and building the tables. The developer can start by building each table within the database, specifying the data type for each and starting to enter some test data. During this phase the database developer also implements the relationships between the tables that were identified earlier.
After the database developer has designed the database and put all the elements in place, the next step is for users to actually test the design and identify potential flaws. Users can enter sample data, or real data, into the database, use the queries the developer has designed and report back any problems they encounter. The database developer uses those test results to improve the performance of the database, at which point the users can retest the application.
The review phase begins after the testing is complete and users are satisfied that the database works the way it should. During this phase the individuals who initially requested the database solution review the results of testing, look at user comments and either sign off on the project or request additional enhancements.