CREATE OR ALTER PROCEDURE REMOVE_CONSTRAINTS AS
DECLARE VARIABLE stmt VARCHAR(255);
begin

    BEGIN
	FOR
		select 'ALTER TABLE '||r.rdb$relation_name
		||' DROP CONSTRAINT '||r.rdb$constraint_name||';'
		from rdb$relation_constraints r
		where (r.rdb$constraint_type='FOREIGN KEY')
		into :stmt
		DO
		BEGIN
			execute statement :stmt;
		end
	END
END

EXECUTE PROCEDURE REMOVE_CONSTRAINTS