根据下拉列表插入数据库

Question

我正在构建一个简单的表单来添加和从数据库表中删除用户。删除用户部分有一个下拉列表控件，可以在数据库中的每个更改后刷新该控件。我设法进行此刷新的唯一方法是在每次更改后刷新页面。我现在有一个非常简单的问题：我希望在每次操作后通过一个简单的标签显示一条消息。但是现在我已经添加了页面刷新，即使使用线程睡眠语句，它也不会再显示。我该怎么做？

请参阅下面的 C# 代码

public partial class _Default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
if (!this.IsPostBack)
{
string CS = ConfigurationManager.ConnectionStrings["EP_PLANNING_NEW"].ConnectionString;
SqlConnection con = new SqlConnection(CS);
{
using (SqlCommand cmd = new SqlCommand("SELECT [ID],[First Name] + ' ' + [Last Name] AS [Full Name] FROM [dbo].[team_members]"))
{
cmd.CommandType = CommandType.Text;
cmd.Connection = con;
try
{
con.Open();
RemUserList.DataSource = cmd.ExecuteReader();
RemUserList.DataTextField = "Full Name";
RemUserList.DataValueField = "ID";
RemUserList.DataBind();
}
catch (Exception ex)
{
throw ex;
}
finally
{
con.Close();
con.Dispose();
}
}
}
RemUserList.Items.Insert(0, new ListItem("- Select Team Member to remove -", "0"));
}
}
protected void RemUserList_SelectedIndexChanged(object sender, EventArgs e)
{
}
protected void AddUserButton_Click(object sender, EventArgs e)
{
string CS = ConfigurationManager.ConnectionStrings["EP_PLANNING_NEW"].ConnectionString;
SqlConnection con = new SqlConnection(CS);
{
SqlCommand cmd = new SqlCommand("INSERT INTO [dbo].[team_members] ([First Name],[Last Name]) VALUES (@FirstName,@LastName)", con);
cmd.Parameters.AddWithValue("@FirstName", AddUserFirstName.Text);
cmd.Parameters.AddWithValue("@LastName", AddUserLastName.Text);
try
{
con.Open();
cmd.ExecuteNonQuery();
}
catch (Exception ex)
{
throw ex;
}
finally
{
con.Close();
con.Dispose();
}
if (IsPostBack)
{
MsgLbl.Text = "** User Successfully Added **";
//System.Threading.Thread.Sleep(2000);
Response.Redirect(Request.RawUrl);
AddUserFirstName.Text = "";
AddUserLastName.Text = "";
}
}
}
protected void RemUserButton_Click(object sender, EventArgs e)
{
string CS = ConfigurationManager.ConnectionStrings["EP_PLANNING_NEW"].ConnectionString;
SqlConnection con = new SqlConnection(CS);
{
SqlCommand cmd = new SqlCommand("DELETE FROM [dbo].[team_members] WHERE [ID] = @ID", con);
cmd.Parameters.AddWithValue("@ID", RemUserList.SelectedValue);
try
{
con.Open();
cmd.ExecuteNonQuery();
}
catch (Exception ex)
{
throw ex;
}
finally
{
con.Close();
con.Dispose();
}
}
if (IsPostBack)
{
MsgLbl.Text = "** User Successfully Removed **";
//System.Threading.Thread.Sleep(2000);
Response.Redirect(Request.RawUrl);
}
}

Answer 1

你不应该重定向到刷新下拉列表，试试下面的代码

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data.SqlClient;
using System.Data;
using System.Configuration;
public partial class _Default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
if (!this.IsPostBack)
{
BindRemUserList();
}
}
protected void BindRemUserList()
{
string CS = ConfigurationManager.ConnectionStrings["EP_PLANNING_NEW"].ConnectionString;
using(SqlConnection con = new SqlConnection(CS))
{
using (SqlCommand cmd = new SqlCommand("SELECT [ID],[First Name] + ' ' + [Last Name] AS [Full Name] FROM [dbo].[team_members]"))
{
cmd.CommandType = CommandType.Text;
cmd.Connection = con;
try
{
con.Open();
RemUserList.DataSource = cmd.ExecuteReader();
RemUserList.DataTextField = "Full Name";
RemUserList.DataValueField = "ID";
RemUserList.DataBind();
}
catch (Exception ex)
{
throw ex;
}
finally
{
con.Close();
con.Dispose();
}
}
}
RemUserList.Items.Insert(0, new ListItem("- Select Team Member to remove -", "0"));
}
protected void RemUserList_SelectedIndexChanged(object sender, EventArgs e)
{
}
protected void AddUserButton_Click(object sender, EventArgs e)
{
string CS = ConfigurationManager.ConnectionStrings["EP_PLANNING_NEW"].ConnectionString;
using(SqlConnection con = new SqlConnection(CS))
{
SqlCommand cmd = new SqlCommand("INSERT INTO [dbo].[team_members] ([First Name],[Last Name]) VALUES (@FirstName,@LastName)", con);
cmd.Parameters.AddWithValue("@FirstName", AddUserFirstName.Text);
cmd.Parameters.AddWithValue("@LastName", AddUserLastName.Text);
try
{
con.Open();
cmd.ExecuteNonQuery();
}
catch (Exception ex)
{
throw ex;
}
finally
{
con.Close();
con.Dispose();
}
MsgLbl.Text = "** User Successfully Added **";
AddUserFirstName.Text = "";
AddUserLastName.Text = "";
BindRemUserList();
}
}
protected void RemUserButton_Click(object sender, EventArgs e)
{
string CS = ConfigurationManager.ConnectionStrings["EP_PLANNING_NEW"].ConnectionString;
using(SqlConnection con = new SqlConnection(CS))
{
SqlCommand cmd = new SqlCommand("DELETE FROM [dbo].[team_members] WHERE [ID] = @ID", con);
cmd.Parameters.AddWithValue("@ID", RemUserList.SelectedValue);
try
{
con.Open();
cmd.ExecuteNonQuery();
}
catch (Exception ex)
{
throw ex;
}
finally
{
con.Close();
con.Dispose();
}
}
MsgLbl.Text = "** User Successfully Removed **";
BindRemUserList();
}
}