How to make sum of 2 columns and show in 3rd column in gridview while data is binding

If you want to do at UI level or BL level, you can create a new datatable as your datasource. For that, define the expected columns from query result and add a new column as sum that you need.

Iterate Row-wise though the datatable you got from DB. Set the values of all the columns row-wise. Lets say, something like:3

foreach (DataRow dr in dt.Rows)
        {
            tempValueIn1stColumn = Convert.ToDouble(dr["1st Column Name"]);
            tempValueIn2ndColumn = Convert.ToDouble(dr["2nd Column Name"]);
            tempValueIn3rdColumn = tempValueIn1stColumn + tempValueIn2ndColumn; 
            // Set the three values in the new table now. 
        }

Though this can be done, but for best performance doing this in database would be advisable.

In GridView, you can use rowdatabound event, in which you can find the third column label control and set the text from your side.

Check from your side.

Thanks.

Mehul Thakkar