Multiple-Column Constraint Format

Use the multiple-column constraint format to associate one or more columns with a constraint. This alternative to the single-column constraint format allows you to associate multiple columns with a constraint. 
(1)
Multiple-Column Constraint Format

1 
2.2.2.1 NOT NULL
2.2.2.1 NULL
2.2.1 UNIQUE
2.2.1 1 DISTINCT
2.1 PRIMARY KEY
1  ( + , column )
1  %CHECK Clause2
Notes:
Element Description Restrictions Syntax
column Name of column or columns on which the constraint is placed Must be unique in a table, but the same name can be in different tables of the same database Identifier

This is a subset of the syntax of Multiple-Column Constraint Format that the CREATE TABLE statement supports.

This alternative to the single-column constraint segment of CREATE TEMP TABLE can associate multiple columns with a constraint. Constraints that you define on temporary tables are always enabled.

The following table indicates where you can find detailed discussions of specific constraints.
Constraint For more information, see For an example, see
CHECK CHECK Clause Defining Check Constraints Across Columns
DISTINCT Using UNIQUE or DISTINCT Constraints Examples of the Multiple-Column Constraint Format
PRIMARY KEY Using the PRIMARY KEY Constraint Defining Composite Primary and Foreign Keys
UNIQUE Using UNIQUE or DISTINCT Constraints Examples of the Multiple-Column Constraint Format

See also the section Differences Between a Unique Constraint and a Unique Index.