sql - 加权平均频率分布

Question

我有以下格式的数据：

TYPE AMOUNT
Book   £2
Pen    £1
Book   £3

我正在尝试将其输出为加权平均值：

TYPE Weighted Average
Book 0.833333333
Pen  0.166666667

到目前为止，我有：

Select TYPE, AMOUNT/SUM(AMOUNT) 
FROM MyTable
Group by TYPE

Answer 1

这应该会给你你想要的结果：

select type
    , cast(sum(amount) as decimal(10,5))/(select sum(amount) from t)
from t
group by type

参见Sql Fiddle 进行演示

Answer 2

这将起作用

DECLARE @Table1 TABLE (TYPE  VARCHAR(10),AMOUNT FLOAT)
INSERT INTO @Table1 SELECT  'Book',2 UNION ALL SELECT 'Pen',1 UNION ALL  SELECT 'Book',3

DECLARE @Total FLOAT
SELECT @Total=SUM(AMOUNT) FROM @Table1

SELECT TYPE,SUM(AMOUNT/@Total) FROM @Table1 GROUP BY TYPE