test=# create table TABLE1 (COL1 int, COL3 int);

CREATE TABLE

test=*# insert into TABLE1 values (1,3);

INSERT 0 1

test=*# commit;

COMMIT

test=# begin;

BEGIN

test=*# create table TABLE1_temp as select COL1, null::int as COL2, COL3 from TABLE1;

SELECT

test=*# drop table TABLE1;

DROP TABLE

test=*# alter table TABLE1_temp rename to TABLE1;

ALTER TABLE

test=*# commit;

COMMIT

test=# select * from TABLE1;