Constraints Compared with Integrities
Constraints check for appropriate data values whenever data is entered in the table. For more information, see the chapter “Managing Tables and Views.”
Integrity refers to integrity objects defined after the table is created to check on update requests before they are allowed to affect the database.
Both mechanisms can be used to ensure data integrity.
Note: Constraints are the ISO Entry SQL92-compliant methods for maintaining database integrity and are, therefore, recommended over integrities. We recommend that you not define both constraints and integrities in the same table.