a 						
	a_id	      a1	 a2				
        ----------------------------
	1	01-01-2001	xxx				
	2	02-02-2002	yyy				
	3	03-03-1999	zzz				
	4	05-05-1988	sss				
							
							

     b 						
	b_id	  b1					
	-------------
        1  	op_1					
	2	op_2					
							
							


     c 						
	c_id	a_id	     a1	         a2   b_id	  b1      c1
        ---------------------------------------------------------------
	1	1	01-01-2001	xxx	 1	op_1	  false
	2	1	01-01-2001	xxx	 2	op_2	  false
	3	2	02-02-2002	yyy	 1	op_1	  false
	4	2	02-02-2002	yyy      2	op_2	  false
	5	3	03-03-1999	zzz	 1	op_1	  false
	6	3	03-03-1999	zzz	 2	op_2	  false
	7	4	05-05-1988	sss	 1	op_1	  false
	8	4	05-05-1988	sss	 2	op_2	  false
							
							

 -- DROP TABLE a;
CREATE TABLE a ( 
   a_id serial NOT NULL,
   a1 date NOT NULL DEFAULT '2001-01-01'::date,
   a2 character varying(55) NOT NULL, 
CONSTRAINT a_pkey PRIMARY KEY (a_id),
CONSTRAINT a_a1a2_key UNIQUE (a1,a2)
)


 -- DROP TABLE b;
CREATE TABLE b ( 
   b_id serial NOT NULL,
   b1 character varying(22) NOT NULL, 
CONSTRAINT b_pkey PRIMARY KEY (b_id),
CONSTRAINT b_b1_key UNIQUE (b1)
)


 -- DROP TABLE c;
CREATE TABLE c ( 
   c_id serial NOT NULL,
   a_id integer NOT NULL references a(a_id),
   a1 date NOT NULL,
   a2 character varying(55) NOT NULL, 
   b_id integer NOT NULL references b(b_id),
   b1 character varying(22) NOT NULL references b(b1), 
   c1 boolean DEFAULT false,
CONSTRAINT c_pkey PRIMARY KEY (c_id)
)



 -- DROP TRIGGER trg_sss ON a;
 -- DROP TRIGGER trg_sss ON b;
 -- DROP FUNCTION add_to_c();


CREATE OR REPLACE FUNCTION add_to_c()
  RETURNS trigger AS
$BODY$
DECLARE
    v1 integer;
    v2 date;
    v3 varchar(55);
BEGIN
IF TG_TABLE_NAME ='a' THEN
        v1 = NEW.a_id;
        v2 = NEW.a1;
        v3 = NEW.a2;
        INSERT INTO c() values (...);
        RETURN NEW;
END IF;

IF TG_TABLE_NAME ='b' THEN
        v1 = NEW.b_id;
        v3 = NEW.b1;
        INSERT INTO c(...) values (...);
        RETURN NEW;
END IF;
END;
$BODY$
  LANGUAGE plpgsql VOLATILE
  COST 100;
ALTER FUNCTION add_to_c()
  OWNER TO wong;

 --

CREATE TRIGGER trg_sss
  AFTER INSERT
  ON a
  FOR EACH ROW
  EXECUTE PROCEDURE add_to_c();

CREATE TRIGGER trg_sss
  AFTER INSERT
  ON b
  FOR EACH ROW
  EXECUTE PROCEDURE add_to_c();

 -- DROP TABLE a;
CREATE TABLE a ( 
   a_id serial NOT NULL,
   a1 date NOT NULL DEFAULT '2001-01-01'::date,
   a2 character varying(55) NOT NULL, 
CONSTRAINT a_pkey PRIMARY KEY (a_id),
CONSTRAINT a_a1a2_key UNIQUE (a1,a2)
);

 -- DROP TABLE b;
CREATE TABLE b ( 
   b_id serial NOT NULL,
   b1 character varying(22) NOT NULL, 
CONSTRAINT b_pkey PRIMARY KEY (b_id),
CONSTRAINT b_b1_key UNIQUE (b1)
);

 -- DROP TABLE c;
CREATE TABLE c ( 
   c_id serial NOT NULL,
   a_id integer NOT NULL,
   b_id integer NOT NULL,
CONSTRAINT c_pkey PRIMARY KEY (c_id)
);


-- заполняю табл. a и b :
INSERT INTO a (a1, a2) values ('1988-01-01', 'xxx');
INSERT INTO a (a1, a2) values ('1989-02-02', 'yyy');
INSERT INTO a (a1, a2) values ('1990-03-03', 'zzz');
INSERT INTO a (a1, a2) values ('1991-04-04', 'sss');
-- 
INSERT INTO b (b1) values ('op_1');
INSERT INTO b (b1) values ('op_2');
INSERT INTO b (b1) values ('op_3');
INSERT INTO b (b1) values ('op_4');
INSERT INTO b (b1) values ('op_5');

INSERT INTO c (a_id, b_id) values (2, 3);
INSERT INTO c (a_id, b_id) values (4, 1);

SELECT a.a_id, a.a1, a.a2, b.b_id, b.b1, TRUE AS c1 FROM b INNER JOIN (a RIGHT JOIN c ON a.a_id = c.a_id) ON b.b_id = c.b_id 
UNION 
SELECT a.a_id, a.a1, a.a2, b.b_id, b.b1, FALSE AS c1 FROM b INNER JOIN (a RIGHT JOIN c ON a.a_id <> c.a_id) ON b.b_id <> c.b_id order by a_id;