In many cases, there are restrictions on table data in a database, such as with respect to value ranges and conditions. For example, when product information is stored in a database, a price cannot be a negative value. This means that no negative value can exist in such a database and values should be checked for this constraint when data is inserted or updated. The purpose of check constraints is to maintain data integrity in the table by checking constraint conditions during data insertion or updating and suppressing the operation if checked data does not satisfy conditions. In this manual, a table for which a check constraint has been defined is called a check constraint table.
Execution of a utility or other operation may cause loss of guaranteed data integrity. In such a case, the check constraint table is placed in check pending status. For details about check pending status, see 12.20.3 Check pending status; for details about operations that cause the loss of guaranteed data integrity, see 12.20.4 Data manipulation and integrity.