Definition of the term "Key field"



A "Key Field" is the ID used to identify a record.

There are two types of Keys:
  • A Primary Key that is used to uniquely identify a record, eg. a teacher record
  • A Unique Key is a key that is composed of two or more field entries used to uniquely identify the record. Eg. birthday, gender, phone number etc.

Example


The Unique Key is composed of the Primary Key (the ID number), The Initials if the Students and their birth years.
ID
#
First
Last
Year
0001DG1993
0001
Daniel
G
1993
0002JB1992
0002
Johann
B
1992

Created by: Daniel Gillo
Last modification: 2nd September 2011

Sources:
  • Jones, Richard. Computer Science Java Enabled. Victoria: IBID Press, 2004