Skip to main content

Complex Entities

The document above represents a College's record of all the courses it offers - one document for each course. Students may take several courses and Tutors may be in charge of more than one course. You will notice that certain data repeats more than once (Student No, Student Name, Date of Birth, Gender and Last Attendance Date) - this is therefore a Complex entity since different courses will have different numbers of students. The structure needs to be converted into its Simple form. The structure will be converted in stages - these stages are called Normal Forms. Here is a summary of the Normal Forms:

  • Un-Normalised Form (UNF)
  • First Normal Form (1NF)
  • Second Normal Form (2NF)
  • Third Normal Form (3NF)

The 3NF version is the simple version of the structure which can be implemented in the database.

Next: Un-Normalised Form (UNF)