■A database consists of multiple relations
■Information about an enterprise is broken up into parts

instructorstudent

advisor

• ■Bad design:
  university(instructor -ID, name, dept_name, salary, student_Id, ..)

  results in

  ●repetition of information (e.g., two students have the same instructor)

  ●the need for null values (e.g., represent an student with no advisor)

• ■Normalization theory deals with how to design“good”

relational schemas