Check Constraint - Definition

Definition

Each check constraint has to be defined in the CREATE TABLE or ALTER TABLE statement using the syntax:

CREATE TABLE table_name ( ..., CONSTRAINT constraint_name CHECK ( predicate ), ... ) ALTER TABLE table_name ADD CONSTRAINT constraint_name CHECK ( predicate )

If the check constraint refers to a single column only, it is possible to specify the constraint as part of the column definition.

CREATE TABLE table_name ( ... column_name type CHECK ( predicate ), ... )

Read more about this topic:  Check Constraint

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