计算mysql中的累积列数

Question

我正在尝试创建累积列但无法创建它，请查看我尝试计算的内容。

mytable

SELECT TotalQuantity AS DistinctTotalQuantity,
       COUNT(TotalQuantity) AS COUNTVALUE, 
       @running_total := @running_total + COUNT(TotalQuantity) AS cumulative_sum
FROM mytable 
JOIN (SELECT @running_total := 0) r
GROUP BY TotalQuantity

根据以上数据集，我想计算明显的计数和累计和

join()

Answer 1

执行累积和的规范ANSI标准方法是通过相关子查询。我在这里使用了一个包含基本查询的视图：

CREATE VIEW test AS
SELECT
    TotalQuantity AS DistinctTotalQuantity,
    COUNT(TotalQuantity) AS COUNTVALUE, 
FROM mytable 
WHERE StoreId = 210 AND ProdName = 'Tusq'
GROUP BY TotalQuantity

然后通过以下方式计算运行总计：

SELECT
    t1.DistinctTotalQuantity,
    t1.COUNTVALUE,
    (SELECT SUM(t2.COUNTVALUE) FROM test t2
     WHERE t2.DistinctTotalQuantity <= t1.DistinctTotalQuantity) AS cumulative_sum
FROM test t1;

使用会话变量我们可以尝试：

SET @total = 0;
SELECT
    DistinctTotalQuantity,
    COUNTVALUE,
    (@total := @total + COUNTVALUE) AS cumulative_sum
FROM test;

Answer 2

以下查询将完美运行，并且您的查询/方法不需要进行太多更改。虽然，我对表现不太确定：

SELECT TotalQuantity AS DistinctTotalQuantity,
       COUNT(TotalQuantity) AS COUNTVALUE, 
       (select @running_total := @running_total + count(TotalQuantity) from mytable m 
     where m.TotalQuantity = m1.TotalQuantity) cumulative_sum
    FROM (select *from mytable order by TotalQuantity) m1
    JOIN (SELECT @running_total := 0) r
    GROUP BY m1.TotalQuantity;

如果要使用浮动值，请按如下方式声明列：

create table `mytable` (
    `TotalQuantity` Decimal (7,1)  //Here 1 is scale. It means 1 digit is allowed after decimal point.
)

这是我更新的Sqlfiddle

希望它有所帮助！

Answer 3

set @csum := 0;
update YourTable
set cumulative_sum = (@csum := @csum + count)
order by id;


set @csum := 0;
select id, count, (@csum := @csum + count) as cumulative_sum
from mytable
order by id;