nulls first 或 nulls last

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#原数据
select * from jinbo.tel_info;
 person |    day     | recevice | miss 
--------+------------+----------+------
 A      | 2018-01-18 |       10 |    0
 B      | 2018-01-18 |        0 |    5
 C      | 2018-01-18 |        4 |    4
 D      | 2018-01-18 |        0 |    0
 E      | 2018-08-27 |        2 |     
(5 rows)

# asc 的时候默认把null 后排， 相当于 order by miss asc nulls last 
select * from jinbo.tel_info order by miss asc;
 person |    day     | recevice | miss 
--------+------------+----------+------
 A      | 2018-01-18 |       10 |    0
 D      | 2018-01-18 |        0 |    0
 C      | 2018-01-18 |        4 |    4
 B      | 2018-01-18 |        0 |    5
 E      | 2018-08-27 |        2 |     
(5 rows)

# asc nulls first
select * from jinbo.tel_info order by miss asc nulls first;
 person |    day     | recevice | miss 
--------+------------+----------+------
 E      | 2018-08-27 |        2 |     
 A      | 2018-01-18 |       10 |    0
 D      | 2018-01-18 |        0 |    0
 C      | 2018-01-18 |        4 |    4
 B      | 2018-01-18 |        0 |    5
(5 rows)

#asc 的时候默认把null 前排， 相当于 order by miss asc nulls first 
select * from jinbo.tel_info order by miss desc;
 person |    day     | recevice | miss 
--------+------------+----------+------
 E      | 2018-08-27 |        2 |     
 B      | 2018-01-18 |        0 |    5
 C      | 2018-01-18 |        4 |    4
 A      | 2018-01-18 |       10 |    0
 D      | 2018-01-18 |        0 |    0


#desc nulls last
select * from jinbo.tel_info order by miss desc nulls last;
 person |    day     | recevice | miss 
--------+------------+----------+------
 B      | 2018-01-18 |        0 |    5
 C      | 2018-01-18 |        4 |    4
 A      | 2018-01-18 |       10 |    0
 D      | 2018-01-18 |        0 |    0
 E      | 2018-08-27 |        2 |     
(5 rows)