SQL statements for implementing integrity constraints

The following SQL statements implement integrity constraints:

CREATE TABLE statement This statement implements integrity constraints during creation of the database.
ALTER TABLE statement This statement adds integrity constraints to an existing database, or modifies constraints for an existing database.
CREATE TRIGGER statement This statement creates triggers that enforce more complex business rules.
CREATE DOMAIN statement This statement creates a user-defined data type. The definition of the data type can include constraints.

For more information about the syntax of these statements, see SQL Statements.