MySQL选择累积（运行总和）列？
要选择累积列，让我们首先创建一个演示表。创建表的查询如下-
mysql> create table accumulatedDemo -> ( -> Value int -> );
使用insert命令在表中插入一些记录。查询如下-
mysql> insert into accumulatedDemo values(10); mysql> insert into accumulatedDemo values(15); mysql> insert into accumulatedDemo values(20); mysql> insert into accumulatedDemo values(25); mysql> insert into accumulatedDemo values(45);
使用select语句显示表中的所有记录。查询如下-
mysql> select *from accumulatedDemo;
这是输出-
+-------+ | Value | +-------+ | 10 | | 15 | | 20 | | 25 | | 45 | +-------+ 5 rows in set (0.00 sec)
以下是选择累积列的查询-
mysql> set @previousSum =0; mysql> select Value, @previousSum: =@previousSum+ Value AS AccumulatedColumn from accumulatedDemo;
这是输出-
+-------+-------------------+ | Value | AccumulatedColumn | +-------+-------------------+ | 10 | 10 | | 15 | 25 | | 20 | 45 | | 25 | 70 | | 45 | 115 | +-------+-------------------+ 5 rows in set (0.00 sec)