CONSTRAINTS 
The system table DOMAIN.CONSTRAINTS contains the CONSTRAINT definitions for all the tables for which the current user has privileges.
Structure
SCHEMANAME |
CHAR(32) |
Name of the schema of the table |
OWNER |
CHAR(32) |
Name of the owner of the table |
TABLENAME |
CHAR(32) |
Name of table with the CONSTRAINT definition |
CONSTRAINTNAME |
CHAR(32) |
Name of the CONSTRAINT definition |
CONSTRAINTTYPE |
CHAR(12) |
Type of the CONSTRAINT definition (CHECK | KEY) |
DEFINITION |
CLOB |
Text of the CONSTRAINT definition |
More Information
Evaluating System Tables, CONSTRAINTS
SQL Reference Manual, CONSTRAINT Definition (constraint_definition)