c# DbHelper

    class DBHelper
    {
        public static string connstr = "server=;database;uid=;pwd=;";
        public int ExecuteNoQuery(string sql,params SqlParameter[] param)
        {
            using (SqlConnection conn = new SqlConnection(connstr))
            {
                conn.Open();
                using(SqlCommand cmd=conn.CreateCommand())
                {
                    cmd.CommandText = sql;
                    cmd.Parameters.AddRange(param);
                    return cmd.ExecuteNonQuery();
                }
            }
        }
        public Object ExecuteScalar(string sql, params SqlParameter[] param)
        {
            using (SqlConnection conn = new SqlConnection(connstr))
            {
                conn.Open();
                using (SqlCommand cmd = conn.CreateCommand())
                {
                    cmd.CommandText = sql;
                    cmd.Parameters.AddRange(param);
                    return cmd.ExecuteScalar();
                }
            }
        }
        public DataTable ExecuteTable(string sql,params SqlParameter[] param)
        {
            using (SqlConnection conn = new SqlConnection(connstr))
            {
                conn.Open();
                using (SqlCommand cmd = conn.CreateCommand())
                {
                    cmd.CommandText = sql;
                    cmd.Parameters.AddRange(param);
                    SqlDataAdapter adapter = new SqlDataAdapter(cmd);
                    DataTable dt = new DataTable();
                    adapter.Fill(dt);
                    return dt;
                }
            }
        }
        public void FillListView(ListView lv,DataTable dt,params string[] headers)
        {
            lv.Clear();
            lv.BeginUpdate();
            for (int i = 0; i < headers.Length;i++ )
            {
                lv.Columns.Add(headers[i],lv.Width/headers.Length-2);
            }
            for (int i = 0; i < dt.Rows.Count;i++ )
            {
                ListViewItem item = new ListViewItem();
                item.Text = dt.Rows[i][0] + "";
                for(int j=1;j<dt.Columns.Count;j++)
                {
                    item.SubItems.Add(dt.Rows[i][j] + "");
                }
                lv.Items.Add(item);
            }
            lv.EndUpdate();
        }
    }