Question

表结构

id | term | result
==================
1  | t1   | 0
2  | t2   | 0
3  | t1   | 34
4  | t1   | 23
5  | t2   | 10
6  | t2   | 10
7  | t3   | 20

该表用于搜索表，其中term是某人搜索的关键字，结果是当时返回的结果数。现在从这个表我需要检索 1）搜索一个术语的次数和 2）上次搜索时返回的结果数。

对于第一个我可以count(term) group by term，而对于2可能ORDER by id DESC，但我不知道如何在一个查询中执行这两个操作。有什么帮助吗？

Answer 1

SELECT term, count, result
FROM   my_table NATURAL JOIN (
         SELECT term, COUNT(*) count, MAX(id) id FROM my_table GROUP BY term
       ) t

在sqlfiddle上查看。

Answer 2

您可以使用GROUP_CONCAT（）函数聚合结果字段，然后使用SUBSTRING_INDEX获取所需的字段。

SELECT COUNT(term), SUBSTRING_INDEX(GROUP_CONCAT(result ORDER BY id DESC), ',', 1) FROM table GROUP BY term

Answer 3

   select term, count(*), (select result from my_table where id = max(t.id)) 
   from my_table t 
   group by term

Answer 4

使用以下查询

      select id,term,count(*) as 'count',result from (select * from table33 
 order by id desc) as abc group by term