Constraints are rules that you can add to your table and column definitions.
These rules govern the data values that can be entered into a table or column.
This module discusses how to
Identify the four basic types of constraints
PRIMARY KEY constraints on database tables
Create unique constraints on database tables
Create foreign key constraints on database tables
CHECK constraints work
EXCEPTIONS INTO clause of the
Identify how constraints are implemented
Find information about constraints in the data dictionary
Adding constraints to the tables and columns in your database helps guarantee the quality of the data in the database. The lower the quality of the
data, the lower the quality of decisions that are made on the data. Since the primary purpose of data collection is to enable intelligent
decisionmaking, the proper use of constraints provides much of the power of your Oracle database.