UPDATE STATEMENT in asp.net using c#

Question

i am using asp.net with C# as code behind

   OleDbConnection cn = new OleDbConnection(@"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=D:\Documents and Settings\CJP\My Documents\Visual Studio 2005\WebSites\NewElligibleSoft\elligiblity.mdb;Persist Security Info=False");
        cn.Open();
        string sql = "UPDATE main SET s_name='"+TextBox1.Text+"',inst_code='"+DropDownList1.SelectedItem+"',ms_oms='"+Label7.Text+"',elligiblity='"+Label12.Text+"',Board='"+DropDownList5.SelectedItem+"',percentage='"+TextBox4.Text+"' WHERE elg_id = '"+DropDownList4.SelectedItem+"'";
        OleDbCommand cmd = new OleDbCommand(sql, cn);
        cmd.ExecuteNonQuery();
        cmd.Dispose();
        cn.Close();
        Response.Write("alert('DATA UPDATED')");

i am getting error on

cmd.ExecuteNonQuery();

that Data type mismatch in criteria expression.

Answer 1

Don't code like

string connection_string="Provider=Microsoft.Jet.OLEDB.4.0;Data Source=D:\Documents and Settings\CJP\My Documents\Visual Studio 2005\WebSites\NewElligibleSoft\elligiblity.mdb;Persist Security Info=False";
using(OleDbConnection cn = new OleDbConnection(connection_string))
{
     cn.Open();
     string sql = "UPDATE main SET s_name=?,inst_code=?,ms_oms=?,elligiblity=?,Board=?,percentage=?,amount=? WHERE elg_id =?";

     using(OleDbCommand cmd = new OleDbCommand(sql, cn))
     {
          cmd.Parameters.Add(new OleDbParameter("s_name",TextBox1.Text.Trim()));
          cmd.Parameters.Add(new OleDbParameter("inst_code",DropDownList1.SelectedItem.Value.ToString()));
          cmd.Parameters.Add(new OleDbParameter("ms_oms",Label7.Text.ToString()));
          cmd.Parameters.Add(new OleDbParameter("elligiblity",Label12.Text));
          cmd.Parameters.Add(new OleDbParameter("Board",DropDownList5.SelectedItem.Value.ToString()));
          cmd.Parameters.Add(new  OleDbParameter("percentage",DropDownList5.SelectedItem.Value.ToString()));
          cmd.Parameters.Add(new OleDbParameter(amount",DropDownList5.SelectedItem.Value.ToString()));
          cmd.Parameters.Add(new OleDbParameter("elg_id",DropDownList5.SelectedItem.Value.ToString()));
          cmd.ExecuteNonQuery();
          cn.Close();
     }
}        
 Response.Write("alert('DATA UPDATED')");