1.2、row_number() —返回行号，不分组

postgres=# select row_number() over(),* from bills limit 2;  
 row_number | id | goodsdesc | beginunit | begincity |       pubtime       | amount  
------------+----+-----------+-----------+-----------+---------------------+---------
          1 |  1 | 衣服      | 海南省    | 三亚市    | 2015-10-05 09:32:01 | 1915.86
          2 |  2 | 建筑设备  | 福建省    | 三明市    | 2015-10-05 07:21:22 | 2022.31
(2 rows)
postgres=# select row_number() over(),* from bills limit 2 offset 2; 
 row_number | id |       goodsdesc       | beginunit | begincity |       pubtime       | amount  
------------+----+-----------------------+-----------+-----------+---------------------+---------
          3 |  6 | 5 0铲车，后八轮翻斗车 | 河南省    | 三门峡市  | 2015-10-05 07:53:13 |  1030.9
          4 |  8 | 旋挖附件38吨          | 河南省    | 三门峡市  | 2015-10-05 10:48:38 | 5365.04
(2 rows)