[postgres:6446@postgres] [12-25.16:58:54]=# select '2015-10-12 14:33'::timestamp ;
      timestamp      
---------------------
 2015-10-12 14:33:00
(1 row)


Time: 0.605 ms
[postgres:6446@postgres] [12-25.17:25:34]=# select '2015-10-12'::timestamp ;
      timestamp      
---------------------
 2015-10-12 00:00:00
(1 row)


Time: 0.323 ms
[postgres:6446@postgres] [12-25.17:25:45]=# select cast('2015-10-12' as timestamp);
      timestamp      
---------------------
 2015-10-12 00:00:00
(1 row)


Time: 0.352 ms
[postgres:6446@postgres] [12-25.17:26:13]=# select cast('2015/10/12' as timestamp);
      timestamp      
---------------------
 2015-10-12 00:00:00
(1 row)


Time: 0.290 ms
[postgres:6446@postgres] [12-25.17:26:28]=# select cast('10/12/2015' as timestamp);
      timestamp      
---------------------
 2015-10-12 00:00:00
(1 row)


Time: 0.380 ms
[postgres:6446@postgres] [12-25.17:26:55]=# select cast('10/12/2015 143321' as timestamp);
      timestamp      
---------------------
 2015-10-12 14:33:21
(1 row)


Time: 0.273 ms
[postgres:6446@postgres] [12-25.17:27:17]=# select cast('10/12/2015 14:33:21' as timestamp);
      timestamp      
---------------------
 2015-10-12 14:33:21
(1 row)


Time: 0.404 ms
[postgres:6446@postgres] [12-25.17:27:24]=# select cast('10/12/2015 08:33:21 pm' as timestamp);
      timestamp      
---------------------
 2015-10-12 20:33:21
(1 row)


Time: 0.404 ms
[postgres:6446@postgres] [12-25.17:27:42]=# select to_timestamp('10/12/2015 14:33:21', 'mm/dd/yyyy hh24:mi:ss');
      to_timestamp      
------------------------
 2015-10-12 14:33:21+08
(1 row)


Time: 0.522 ms
[postgres:6446@postgres] [12-25.17:29:02]=# select '10/12/2015 08:33:21 pm'::timestamp;
      timestamp      
---------------------
 2015-10-12 20:33:21
(1 row)


Time: 0.269 ms

[postgres:6446@postgres] [12-25.17:32:23]=# select to_char(now(),'yyyy/mm/dd');
  to_char   
------------
 2015/12/25
(1 row)

[postgres:6446@postgres] [12-25.17:31:46]=# select now()::varchar(19);
         now         
---------------------
 2015-12-25 17:31:57
(1 row)
[postgres:6446@postgres] [12-25.17:31:31]=# select now()::varchar;
              now              
-------------------------------
 2015-12-25 17:31:38.593149+08
(1 row)


Time: 0.574 ms