using(SqlConnection conn = new SqlConnection(connectionString))
            {
                using(SqlCommand cmd = new SqlCommand(sql, conn))
                {
                    try
                    {
                        PrepareCommand(cmd, conn, null, sql, cmdParms);
                        cmd.ExecuteNonQuery();
                        cmd.Parameters.Clear();
                        return true;
                    }
                    catch (SqlException ex)
                    {
                        cmd.Dispose();
                        conn.Close();
                        return false;
                    }
                }
            }

如果把上面的

cmd.Dispose();
conn.Close();

去掉， 效果是不是一样的啊?