Page 5 - Relational Databases

 Criteria for the candidate keys:
 It must contain unique values
 It must not contain null values
 It contains the minimum number of fields to ensure uniqueness
 It must uniquely identify each record in the table

Foreign Key
• A foreign key is a field (or collection of fields) in one table that is a primary key of
other table.
• Creates a relationship between two tables/relations.
Dno/Dname is the foreign key in the DB below.