i have sql table 1 that contains itemcode - itemcount - tablename
and my windows form1 contains listview1 and button1
what i'm trying to do is that when i click on button1 all listview1 SubItems[1]  values in the column to update  from tables names in SubItems[2]  values where  itemcode  values are SubItems[0]  
i tried the following code but it did what it should do but for the first row only not the rest: 
foreach (ListViewItem item in listView1.Items)
             {
                 item.Selected = true;
             }
             if (cn.State == ConnectionState.Closed) cn.Open();
             cm = new SqlCommand();
             cm.Connection = cn;
              ListViewItem lvi1 = listView1.SelectedItems[0];
             string tableName = lvi1.SubItems[2].Text;
             string itemcode1 = lvi1.SubItems[0].Text;
             string itemcode2 = lvi1.SubItems[1].Text;
              string sql = "UPDATE " + tableName + " SET [itemcount]= " + itemcode2 + " WHERE [itemcode]= " + itemcode1 + " AND [itemcount] IS NOT NULL";
             cm.CommandText = sql;
             cm.ExecuteNonQuery();