ROLLBACK

Roll back the current transaction, discarding any changes that the transaction would have committed.

ROLLBACK [ WORK | TRANSACTION ]

For example, the season table is not dropped because the ROLLBACK command ends the transaction:

premdb=# begin;
BEGIN
premdb=# drop table season;
DROP TABLE
premdb=# rollback;
ROLLBACK
premdb=# \d season
              Table "public.season"
   Column    |         Type          | Modifiers 
-------------+-----------------------+-----------
 seasonid    | smallint              | 
 season_name | character(9)          | 
 numteams    | smallint              | 
 winners     | character varying(30) | 

Distribution: Replicated

If no transaction is in progress, the ROLLBACK command returns a warning and has no other effect:

premdb=# rollback;
WARNING:  there is no transaction in progress
ROLLBACK