如何使用C＃从ASP.NET中的SQL Server设置数据范围

Question

I am creating a page on which there is a map of India. I have inserted data into the SQL Server database about economic indicators. I have also placed a map of India on the webpage.

I want to be able to retrieve the data from the database and then get the greatest value from the data and set it as 100%. Then based on that if a value falls between 0 to 20% a that part of the map should be a certain color. If it falls between 20 to 40% it will be a different color and so on.

I am new to ASP.NET and SQL Server and not sure how to do this. I really need help. Thank you in advance

Answer 1

Try something like this.

WITH cte 
     AS (SELECT states, 
                value, 
                ( value / NULLIF(Max(value) 
                                   OVER(), 0) ) * 100 AS [Percent] 
         FROM   yourtable) 
SELECT states, 
       value, 
       color = CASE 
                 WHEN [percent] BETWEEN 0 AND 20 THEN 'X color' 
                 WHEN [percent] BETWEEN 21 AND 40 THEN 'Y color' 
                 WHEN [percent] BETWEEN 41 AND 60 THEN 'X color' 
                 .....
               END 
FROM   cte 

Notes :

• Formula used to calculate percentage (Value/max_value) * 100 . Please correct if it is wrong.
• Considering value as the column for which you need to find percentage
• NULLIF is used to avoid divide by zero error
• Max() Over() is to find the largest value in your table