i want to know how can i show sum of individual columns in gridview?

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C#

ASP.NET

SQL-Server

i have 6 columns (salary,ta,contingency,nrc,institcharges,others) in my gridview what i wanna do is i want to get the sum of each column in the footer of each column. for this i have taken template fields and inserted a label in them but my problem is in my coding the result i am getting is total of all the columns on each label

this is the code i m using in my code behind file:

int total = 0;
 protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
    {



        if (e.Row.RowType == DataControlRowType.DataRow)
        {
            total += Convert.ToInt32(DataBinder.Eval(e.Row.DataItem, "salary"));
        }
        if (e.Row.RowType == DataControlRowType.Footer)
        {
            Label sallabel = (Label)e.Row.FindControl("sallabel");
            sallabel.Text = total.ToString();
        }

        if (e.Row.RowType == DataControlRowType.DataRow)
        {
            total += Convert.ToInt32(DataBinder.Eval(e.Row.DataItem, "ta"));
        }
        if (e.Row.RowType == DataControlRowType.Footer)
        {
            Label lblamount2 = (Label)e.Row.FindControl("talabel");
            lblamount2.Text = total.ToString();

        }
        if (e.Row.RowType == DataControlRowType.DataRow)
        {
            total += Convert.ToInt32(DataBinder.Eval(e.Row.DataItem, "contigency"));
        }
        if (e.Row.RowType == DataControlRowType.Footer)
        {
            Label lblamount3 = (Label)e.Row.FindControl("cnlabel");
            lblamount3.Text = total.ToString();
        }

        if (e.Row.RowType == DataControlRowType.DataRow)
        {
            total += Convert.ToInt32(DataBinder.Eval(e.Row.DataItem, "nrc"));
        }
        if (e.Row.RowType == DataControlRowType.Footer)
        {
            Label lblamount4 = (Label)e.Row.FindControl("nrclabel");
            lblamount4.Text = total.ToString();

        }

        if (e.Row.RowType == DataControlRowType.DataRow)
        {
            total += Convert.ToInt32(DataBinder.Eval(e.Row.DataItem, "institcharges"));
        }
        if (e.Row.RowType == DataControlRowType.Footer)
        {
            Label lblamount5 = (Label)e.Row.FindControl("iclabel");
            lblamount5.Text = total.ToString();
        }

        if (e.Row.RowType == DataControlRowType.DataRow)
        {
            total += Convert.ToInt32(DataBinder.Eval(e.Row.DataItem, "others"));
        }
        if (e.Row.RowType == DataControlRowType.Footer)
        {
            Label lblamount6 = (Label)e.Row.FindControl("olabel");
            lblamount6.Text = total.ToString();
        }

    }