用于3行值的集合类型，其中2个必须相乘

i am returning results from a sql query which contains multiple rows of three columns. Column1(a rate) must be multiplied by column2(a numerical value). Column 3 consists of five different possible values. Each value will indicate a condition that column1 and column2 must adhere to( basically column3 will be another value (like an exchange rate)- but it has not yet been determined, so I would like to group this value with the result of the other two. Obviously a collection of some sort ought to be used, but i am not sure which will allow me to efficiently deal with multiplying column1 by column2 and noting the value for column3 and multiplying this at a later date. So far, I have something like this: (obviously ill probably need a for loop)i am returning results from a sql query which c