时间：2021-09-14 15:05:08 | 栏目：PostgreSQL | 点击：次
我就废话不多说了，大家还是直接看代码吧~
select * from (select ROW_NUMBER () OVER (ORDER BY fat desc nulls last) AS xuhao,foodnum,foodname,fat from ek_food where isdel=0) food where foodnum = 'Ss192008'
1.排序时，字段值为null的会排在前面，导致数据不准确，解决办法 在order by后面增加 nulls last
2.给查询的结果增加序号 select ROW_NUMBER () OVER (ORDER BY fat desc nulls last) AS xuhao
补充：利用 PostgreSQL 实现对数据进行排名
| user_id | name | score |
| 1 | john | 1000 |
| 2 | mike | 1200 |
| 3 | jelly | 1300 |
| 4 | brook | 1500 |
| 5 | nanny | 1200 |
需要知道 user_id = k 的用户对应的积分排名
SELECT user_id, name, score, RANK() OVER (ORDER BY score DESC) FROM user;
| user_id | name | score | rank |
| 4 | brook | 1500 | 1 |
| 3 | jelly | 1200 | 2 |
| 2 | mike | 1300 | 3 |
| 5 | nanny | 1500 | 3 |
| 1 | john | 1200 | 5 |
如要获取排名 < 3 的用户：
SELECT user_id, name, score, user_rank FROM (SELECT user_id, name, score, RANK() OVER (ORDER BY score DESC) AS user_rank FROM user) AS T WHERE user_rank < 3;
-- 注意子查询在from中需要写别名
| user_id | name | score | rank |
| 4 | brook | 1500 | 1 |
| 3 | jelly | 1200 | 2 |