计算MySql中的百分比(Calculate Percentage in MySql)

 我想根据我桌子的特定产品的数量来计算百分比。我想根据下表的计算添加百分比列。表格列是： 
 
Item_Category : It gives the item name
Item_Amount : It gives the sum of the particular item
 
 我使用的查询是： 
 
select Item_Category,
      (SUM(Item_Amount)/100000) as Total,
      quarter(Invoice_date) as Quarter,
      year(Invoice_date) as Year 
from `cmpsldata` 
where Site='BDD1' 
      and Item_code LIKE 'FG%' 
      and Invoice_type='Excise'    
group by Year,Item_Category,Quarter 
order by Total desc

Table : 
| Item_Category | Total | Quarter | Year |
| Product A     | 78.65 | 1       | 2015 |
| Product B     | 65.54 | 1       | 2015 |
| Product C     | 45.78 | 1       | 2015 |
 
 这是当前表格，我现在需要再添加一列，这样我就可以得到产品A，B，C的百分比计算（单独）。 

I want to calculate percentage on basis on amount for a particular product for my table.I want to add percentage column on basis of the calculation according to the following table.The table column are : 
 
Item_Category : It gives the item name
Item_Amount : It gives the sum of the particular item
 
The query which i have used is : 
 
select Item_Category,
      (SUM(Item_Amount)/100000) as Total,
      quarter(Invoice_date) as Quarter,
      year(Invoice_date) as Year 
from `cmpsldata` 
where Site='BDD1' 
      and Item_code LIKE 'FG%' 
      and Invoice_type='Excise'    
group by Year,Item_Category,Quarter 
order by Total desc

Table : 
| Item_Category | Total | Quarter | Year |
| Product A     | 78.65 | 1       | 2015 |
| Product B     | 65.54 | 1       | 2015 |
| Product C     | 45.78 | 1       | 2015 |
 
This is the current table now i need to add 1 more column which gives me percentage calculation of the Product A, B , C(individually).

原文：https://stackoverflow.com/questions/32322901