The design process in DBMS Further

Storing information about

- In this example the file is storing information about:
• the staff members who attending courses
• the departments in which those staff members work
• the courses that are being offered
• the actual attendance of an employee on a course

- the above problems could be avoided if we can keep the
information about each of these things separately, and then
make cross-references where required (relational database approach)


Relational database approach

- In a relational database, the data values held are
stored in tables (an arrangement of rows and columns, just like a spread sheet)

- one of the main advantage is its ability to set up and automatically maintain cross-references
(relationships) between the tables.
- the structure that hold the data is called a ‘relation’. Common term is table. A row is called a
‘tuple’ and a column is called an ‘attribute’.

Dr.E.F.Codd invented these new words.

A systematic approach to DB design

- implementing large information system can be extremely complicated
- break down the work into series of steps, and each step into manageable tasks.
- the basic steps to be followed during the design and construction are as follows.
• Decide what is the purpose of the DB
• Determine the information requirements of the DB
• Produce a logical model of the information requirements of DB
• Convert the logical data model to a physical data model appropriate to the technology being used
• Implement the physical design using the chosen method or product