create database test;

\connect test

CREATE TABLE "t2" (
	"nr2" integer,
	"t1" integer
);

CREATE TABLE "t1" (
	"nr1" integer,
	"typ" integer,
	"art" integer
);

CREATE VIEW "feld" as SELECT * FROM t1, t2 WHERE t1.nr1 = t2.t1 UNION
 SELECT *, null, null FROM t1 WHERE t1.art = 1;

insert into t2 values(4,	4);
insert into t2 values(3,	3);

insert into t1 values(1,	1,	1);
insert into t1 values(2,	2,	1);
insert into t1 values(3,	1,	2);
insert into t1 values(4,	2,	2);

select * from feld where typ=1;

\c 

drop database test;