How to increment string value in asp.net using for loop

Question

My code is here I am getting an error during the run program.

 

for (int date= Convert.ToInt16(concat1) ; date>Convert.ToInt16(concat); concat=(concat+1))

{

MySqlConnection connection = new MySqlConnection(ConfigurationManager.ConnectionStrings["Datavos3000"].ConnectionString.ToString());

string str = "select id as CallerID,feetime as Duration,fee as Charge,callere164 as Gateway_ID,calleee164 as Number_Dialled,callerip as Caller_IP from " + concat + " where feetime>0 or customeraccount='" + Hidden.Value + "' group by customeraccount limit 1000;";

MySqlCommand cmd = new MySqlCommand(str, connection);

MySqlDataAdapter adapter = new MySqlDataAdapter(cmd);

DataTable set = new DataTable();

connection.Open();

adapter.Fill(set);

grid.DataSource = set;

grid.DataBind();

connection.Close();

}

 

 Please Help me.