how to pass pass value member in StringBuilder form cheackedlistbox

//***********************************************************************************
public void FillCheckedListBox1party()
        {
            try
            {
                if (con.State == ConnectionState.Closed)
                {
                    con.Open();
                }

                string commandString = "SELECT NAME ,AC_CODE FROM AccountM where compcode='" + Compcls.Gcomp_cd + "'";
               
                DataTable accTable = new DataTable();
                SqlCommand cmd = new SqlCommand(commandString, con);
                SqlDataAdapter adpObj = new SqlDataAdapter(cmd);
                accTable.TableName = "tbl";
                adpObj.Fill(accTable);
                con.Close();
                checkedListBox1.DataSource = accTable;
                checkedListBox1.ValueMember = "AC_CODE";
                checkedListBox1.DisplayMember ="NAME";
            }
            catch (Exception ex)
            {

                throw ex;
            }
            finally
            {
                con.Close();
            }

if (con.State == ConnectionState.Closed)
           {
               con.Open();
           }
           StringBuilder query = new StringBuilder("SELECT ITEMCODE, BROKTYPE,BROKRATE,TRANRATE,TranType,uptostdt,MARTYPE,MARRATE FROM PITBROK ");
           query.AppendFormat("where    ");
           for (int i = 0; i < checkedListBox1.CheckedItems.Count; i++)
           {
               int coun = checkedListBox1.CheckedItems.Count;
               coun = coun - 1;

query.AppendFormat("PITBROK.AC_CODE='{0}' ", checkedListBox1.CheckedItems[value]);

               if (i < coun)
               {
                   query.AppendFormat("  and    ");
               }