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2.1.1.1 Check Constraints

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A check constraint specifies a validation condition that MUST be satisfied for data to be added or updated in a table. A check constraint can be defined either as a table-wide constraint or on a specific column in the table. When a check constraint is added to a table, the constraint can optionally be tested on existing data. A check constraint can also optionally specify a message to be displayed to the user when the data violates the validation condition.

This protocol defines the CheckConstraint element (section 2.2.1.6) for specifying a check constraint.