如何将数据库中的数据显示到文本框中，并更新它

Question

在从 sql 数据库检索数据后，我可以在我的文本框、下拉列表中显示我的数据，但是当我继续使用更新按钮时，在文本框或下拉列表中编辑的信息不会更新到数据库中。我试图在页面加载中删除代码，并手动重新键入所有数据，它可以更新。我想要的只是从数据库中检索数据并将其显示在文本框中，并且可以在从文本框中进行一些更改后将其更新到数据库中。有人可以帮我吗？谢谢。

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.Configuration;
using System.Data;
public partial class UpdateCustomerDetails : System.Web.UI.Page
{

protected void Page_Load(object sender, EventArgs e)
{
    SqlConnection con1 = new SqlConnection("Data Source=USER-PC;Initial Catalog=webservice_database;Integrated Security=True");
    DataTable dt = new DataTable();
    con1.Open();
    SqlDataReader myReader = null;  
    SqlCommand myCommand = new SqlCommand("select * from customer_registration where username='" + Session["username"] + "'", con1);

    myReader = myCommand.ExecuteReader();

    while (myReader.Read())
    {
        TextBoxPassword.Text = (myReader["password"].ToString());
        TextBoxRPassword.Text = (myReader["retypepassword"].ToString());
        DropDownListGender.SelectedItem.Text = (myReader["gender"].ToString());
        DropDownListMonth.Text = (myReader["birth"].ToString());
        DropDownListYear.Text = (myReader["birth"].ToString());
        TextBoxAddress.Text = (myReader["address"].ToString());
        TextBoxCity.Text = (myReader["city"].ToString());
        DropDownListCountry.SelectedItem.Text = (myReader["country"].ToString());
        TextBoxPostcode.Text = (myReader["postcode"].ToString());
        TextBoxEmail.Text = (myReader["email"].ToString());
        TextBoxCarno.Text = (myReader["carno"].ToString());
    }
    con1.Close();
}
protected void Button1_Click(object sender, EventArgs e)
{
    SqlConnection con = new SqlConnection("Data Source=USER-PC;Initial Catalog=webservice_database;Integrated Security=True");
    SqlCommand cmd = new SqlCommand("UPDATE customer_registration SET password = @password, retypepassword = @retypepassword, gender = @gender, birth = @birth, address = @address, city = @city, country = @country, postcode = @postcode, email = @email, carno = @carno where username='" + Session["username"] + "'", con);
    con.Open();

    cmd.Parameters.AddWithValue("@password", TextBoxPassword.Text);
    cmd.Parameters.AddWithValue("@retypepassword", TextBoxRPassword.Text);
    cmd.Parameters.AddWithValue("@gender", DropDownListGender.Text);
    cmd.Parameters.AddWithValue("@birth", DropDownListDay.Text + DropDownListMonth.Text + DropDownListYear.Text);
    cmd.Parameters.AddWithValue("@address", TextBoxAddress.Text);
    cmd.Parameters.AddWithValue("@city", TextBoxCity.Text);
    cmd.Parameters.AddWithValue("@country", DropDownListCountry.Text);
    cmd.Parameters.AddWithValue("@postcode", TextBoxPostcode.Text);
    cmd.Parameters.AddWithValue("@email", TextBoxEmail.Text);
    cmd.Parameters.AddWithValue("@carno", TextBoxCarno.Text);

    cmd.ExecuteNonQuery();
    con.Close();
    if (IsPostBack)
    {
        Response.Redirect("UpdateSuccess.aspx");
    }
}

Answer 1

在 Page Init 事件中填充文本框值，而不是使用 Postback。

protected void Page_Init(object sender, EventArgs e)
{
    DropDownTitle();
}

Answer 2

protected void Page_Load(object sender, EventArgs e)

    {

        DropDownTitle();
    }


protected void DropDownTitle()
{
    if (!Page.IsPostBack)
    {

        string connection = System.Configuration.ConfigurationManager.ConnectionStrings["AuzineConnection"].ConnectionString;

        string selectSQL = "select DISTINCT ForumTitlesID,ForumTitles from ForumTtitle";
        SqlConnection con = new SqlConnection(connection);
        SqlCommand cmd = new SqlCommand(selectSQL, con);
        SqlDataReader reader;
        try
        {

            ListItem newItem = new ListItem();
            newItem.Text = "Select";
            newItem.Value = "0";
            ForumTitleList.Items.Add(newItem);
            con.Open();
            reader = cmd.ExecuteReader();



            while (reader.Read())
            {
                ListItem newItem1 = new ListItem();
                newItem1.Text = reader["ForumTitles"].ToString();
                newItem1.Value = reader["ForumTitlesID"].ToString();
                ForumTitleList.Items.Add(newItem1);



            }
            reader.Close();
            reader.Dispose();
            con.Close();
            con.Dispose();
            cmd.Dispose();


        }
        catch (Exception ex)
        {
            Response.Write(ex.Message);
        }

    }
}

Answer 3

答案是@Kundan Singh Chouhan 建议的.IsPostBack。只是添加到它，将您的代码移动到 Page_Load 的单独方法中

private void PopulateFields()
{
  using(SqlConnection con1 = new SqlConnection("Data Source=USER-PC;Initial Catalog=webservice_database;Integrated Security=True"))
  {
    DataTable dt = new DataTable();
    con1.Open();
    SqlDataReader myReader = null;  
    SqlCommand myCommand = new SqlCommand("select * from customer_registration where username='" + Session["username"] + "'", con1);

    myReader = myCommand.ExecuteReader();

    while (myReader.Read())
    {
        TextBoxPassword.Text = (myReader["password"].ToString());
        TextBoxRPassword.Text = (myReader["retypepassword"].ToString());
        DropDownListGender.SelectedItem.Text = (myReader["gender"].ToString());
        DropDownListMonth.Text = (myReader["birth"].ToString());
        DropDownListYear.Text = (myReader["birth"].ToString());
        TextBoxAddress.Text = (myReader["address"].ToString());
        TextBoxCity.Text = (myReader["city"].ToString());
        DropDownListCountry.SelectedItem.Text = (myReader["country"].ToString());
        TextBoxPostcode.Text = (myReader["postcode"].ToString());
        TextBoxEmail.Text = (myReader["email"].ToString());
        TextBoxCarno.Text = (myReader["carno"].ToString());
    }
    con1.Close();
  }//end using
}

然后在你的 Page_Load 中调用它

protected void Page_Load(object sender, EventArgs e)
{

    if(!Page.IsPostBack)
    {
       PopulateFields();
    }
}

Answer 4

在页面加载时将所有语句包装在 !IsPostBack 条件中。

protected void Page_Load(object sender, EventArgs e)
{
   if(!IsPostBack)
   {
      // all statements
   }
}

这将解决您的问题。