SYSCONSTRAINT system table

CREATE TABLE SYS.SYSCONSTRAINT (
	constraint_id unsigned int NOT NULL,
	table_id nsigned int NOT NULL,
	column_id unsigned int NULL,
	index_id unsigned int NULL,
	fkey_id mallint NULL,	
	constraint_type char(1) NOT NULL,
	constraint_name char(128) NOT NULL,

	PRIMARY KEY( constraint_id ),
	UNIQUE( table_id, constraint_name )
)

Each row describes a named constraint.

constraint_id The unique constraint ID.

table_id The table ID of the table to which the constraint applies.

column_id The column ID of the column to which the constraint applies. The column is NULL for any constraints that are not column constraints.

index_id The index ID for a unique constraint. The column is NULL for all constraints that are not unique constraints.

fkey_id The foreign key ID for a foreign-key constraint. The column is NULL for all constraints that are not foreign-key constraints.

constraint_type Set to one of the following values:

C is the constraint is a column check constraint.
T if the constraint is a table constraint.
P if the constraint is a primary key.
F if the constraint is a foreign key.
U if the constraint is a unique constraint.

constraint_name The name of the constraint.