MySQL查询获取最大累积值
为此,将聚合函数COUNT(*)与子查询一起使用。还使用GROUP BY。
让我们创建一个表-
mysql> create table demo23−> (
−> id int not null auto_increment primary key,
−> value1 int,
−> value2 int
−> );
借助insert命令将一些记录插入表中-
mysql> insert into demo23(value1,value2) values(5,600);mysql> insert into demo23(value1,value2) values(20,800);
mysql> insert into demo23(value1,value2) values(7,400);
mysql> insert into demo23(value1,value2) values(6,500);
mysql> insert into demo23(value1,value2) values(10,300);
mysql> insert into demo23(value1,value2) values(11,500);
使用select语句显示表中的记录-
mysql> select *from demo23;
这将产生以下输出-
+----+--------+--------+| id | value1 | value2 |
+----+--------+--------+
| 1 | 5 | 600 |
| 2 | 20 | 800 |
| 3 | 7 | 400 |
| 4 | 6 | 500 |
| 5 | 10 | 300 |
| 6 | 11 | 500 |
+----+--------+--------+
6 rows in set (0.00 sec)
以下是最大累积量的查询-
mysql> select total_value, count(*) as number_of_occurrences−> from (
−> select value1*value2 as total_value
−> from demo23
−> ) t
−> group by total_value
−> order by total_value desc
−> limit 1 ;
这将产生以下输出-
+-------------+-----------------------+| total_value | number_of_occurrences |
+-------------+-----------------------+
| 16000 | 1 |
+-------------+-----------------------+
1 row in set (0.00 sec)
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