将一个使用块包装在另一个使用块内 - 是否有点过分？

Question

我在我的项目中有一段代码,我在另一个使用块中包含一个使用块,我想知道这是一个好习惯还是矫枉过正(请注意我明白这是一个非常简单的代码片段,它是仅用于说明目的):

protected void Submit_Click(object sender, EventArgs e)
    {
        try
        {
            using (SqlConnection cn = new SqlConnection(ConfigurationManager.ConnectionStrings["RegConnectionString"].ConnectionString))
            {
                cn.Open();

                string cmdStr = "SELECT COUNT(*) FROM REGISTRATION WHERE UserName ='" + this.TextBoxUN.Text + "' ";
                using (SqlCommand selectUser = new SqlCommand(cmdStr, cn))
                {
                    int temp = Convert.ToInt32(selectUser.ExecuteScalar().ToString());

                    if (temp == 0)
                    {
                        string insCmd = "Insert INTO REGISTRATION (UserName, Password, EmailAddress, FullName, Country) VALUES (@UserName, @Password, @EmailAddress, @FullName, @Country)";
                        using (SqlCommand insertUser = new SqlCommand(insCmd, cn))
                        {
                            try
                            {
                                insertUser.Parameters.AddWithValue("@UserName", this.TextBoxUN.Text);
                                insertUser.Parameters.AddWithValue("@Password", this.TextBoxPass.Text);
                                insertUser.Parameters.AddWithValue("@EmailAddress", this.TextBoxEA.Text);
                                insertUser.Parameters.AddWithValue("@FullName", this.TextBoxFN.Text);
                                insertUser.Parameters.AddWithValue("@Country", this.DropDownListCountry.SelectedItem.ToString());

                                insertUser.ExecuteNonQuery();
                                Response.Redirect("~/Login.aspx");
                            }
                            catch (Exception ex)
                            {
                                Response.Write(ex.Message);
                            }
                        }
                    }
                    else
                    {
                        Response.Write("User already Exists in Database");
                    }
                }
            }
        }
        catch (Exception ex)
        {
            Response.Write(ex.Message);
        }
    }
}

Answer 1

是.好的做法.在尽可能小的范围内处理物品,否则你将它留在GC做一段时间以后.