Creating Constraints¶
A constraint can be created at table creation using CREATE TABLE, or added to a table later using ALTER TABLE:
- Single-column constraints can be created inline as part of the column definition.
- Multi-column constraints must be created in a separate, i.e. out-of-line, clause that specifies the columns in the constraint.
To create a constraint, certain access control privileges must be granted on the role used to create the constraint. For more information, see the security details described in Additional Constraint Details.
In this Topic:
Creating Constraints Inline¶
The following inline syntax can only be used for single-column constraints:
CREATE [OR REPLACE] TABLE <name> (<column_name> <column_type> [ <inline_constraint> ] , ... )
ALTER TABLE <name> ADD COLUMN <column_name> <column_type> [ <inline_constraint> ]
For inline_constraint
syntax details, see CREATE | ALTER TABLE … CONSTRAINT.
Creating Constraints Out-of-line¶
The following out-of-line syntax must be used for multi-column constraints, but can also be used for single-column constraints:
CREATE [OR REPLACE] TABLE <name> ( ... , [ <outofline_constraint> ], ... )
ALTER TABLE <name> ADD <outofline_constraint>
For outofline_constraint
syntax details, see CREATE | ALTER TABLE … CONSTRAINT.