CREATE TEMPORARY TABLE t1 (i INT, t TEXT) USING memoryam;
INSERT INTO t1 VALUES (1, 'hello');
INSERT INTO t1 VALUES (2, 'world');
SELECT * FROM t1;
 i |   t   
---+-------
 1 | hello
 2 | world
(2 rows)

UPDATE t1 SET t = 'foo' WHERE i = 2;
SELECT * FROM t1;
 i |   t   
---+-------
 1 | hello
 2 | foo
(2 rows)

UPDATE t1 SET t = 'bar', i = 3 WHERE i = 1;
SELECT * FROM t1;
 i |  t  
---+-----
 2 | foo
 3 | bar
(2 rows)

DROP TABLE t1;