Chapter 7, Problem 11SCG

Program Plan Intro

Foreign key:

• A primary key attribute in one table is the foreign key for another table. In logical way, a foreign key is used to establish a relationship between two tables.
• A foreign key is used for identifying a row of another table uniquely.
• Foreign keys are represented in italic form.

ALTER TABLE Statement:

• “ALTER TABLE” statement comes under Data Definition Language (DDL).
• It is used to modify column, add constraints, add column(s), drop column, rename column name and table name, drop constraints, and so on.

Syntax:

The Syntax to drop constraint is as follows:

ALTER TABLE table_Name ADD CONSTRAINT constraint_Name;