evaluate variable values ( manipulating variables and valu )

i have 2 tables

1. report table (with fields (cols))

col1, col2, col3, col4, col5, col6, col7

values in row 1

col1 = "trx_no"

col2 = "trx_date"

col3 = "quantity"

col4 = "rate"

col4 = "quantity * rate"

col6 = "tax"

col7 = "(quantity * rate)+tax"

2. transaction table (with fields (cols))

trx_no, trx_date, quantity, rate, tax

value in row 1

trx_no = "00001"

trx_date = "01/04/2020"

quantity = 20

rate = 150

tax = 540

value in row 2

trx_no = "00002"

trx_date = "05/04/2020"

quantity = 100

rate = 110

tax = 1980

private void TData_Grid(string RMST)
{
if (SPDConn.State != ConnectionState.Open) // Connection can be {Open, Close, Broken, Connnecting, Executing, Fetching}
{
SPDConn.Close();
SPDConn.Open();
}
if (SPMConn.State != ConnectionState.Open) // Connection can be {Open, Close, Broken, Connnecting, Executing, Fetching}
{
SPMConn.Close();
SPMConn.Open();
}
string str1 = "select * from dbo.trxdat" + SPGlobal.spyear + " where cmp_code = '" + SPGlobal.spcmp_code + "' and trx_type = '" + RMST + "'";
SqlCommand mcmd = new SqlCommand(str1, SPDConn);
SqlDataReader mrdr = mcmd.ExecuteReader();
string trx_no;
DateTime trx_date;
decimal quantity, rate, tax;
while (mrdr.Read())
{
//transfering datatable to variables
trx_no = mrdr["trx_no"].ToString();
trx_date = (DateTime)mrdr["trx_date"];
quantity = (decimal)mrdr["quantity"];
rate = (decimal)mrdr["rate"];
tax = (decimal)mrdr["tax"];
Console.WriteLine(col1);
Console.WriteLine(col2);
Console.WriteLine(col3);
Console.WriteLine(col4);
Console.WriteLine(col5);
Console.WriteLine(col6);
Console.WriteLine(col7);
}
mrdr.Close();
}

how do i manupulate col1, col2, col3, ...... so that at console i get

note : datatables won't change they are read only

"00001"

"01/04/2020"

150

3000

540

3540