A constraintName represents a constraint (see
CONSTRAINT clause).
Syntax[ schemaName. ] SQLIdentifier
You can qualify a constraintName with a schemaName, but the
schemaName of the constraint must be the same as the schemaName of
the table on which the constraint is placed.
Example-- country_fk2 is a constraint name
CREATE TABLE DETAILED_MAPS (COUNTRY_ISO_CODE CHAR(2)
CONSTRAINT country_fk2 REFERENCES COUNTRIES)-- s1.c1 is a schema-qualified constraint; the schema name
-- is not required here, but if specified must match that of the table
CREATE SCHEMA s1;
CREATE TABLE s1.t1 ( a INT, CONSTRAINT s1.c1 CHECK ( a > 0 ) );