CREATE table t1 (c1 integer, c2 integer)
INSERT INTO t1 VALUES (0, 10)
INSERT INTO t1 VALUES (0, 10)
INSERT INTO t1 VALUES (2, 20)
INSERT INTO t1 VALUES (2, 20)
DROP table t2
CREATE table t2 (c1 integer, c2 integer)
INSERT INTO t2 VALUES (2, 20)
INSERT INTO t2 VALUES (2, 20)
INSERT INTO t2 VALUES (3, 30)
INSERT INTO t2 VALUES (3, 30)
UPDATE t1 SET t1.c1 = 1 FROM t2 WHERE t1.c2 = t2.c2