下拉列表重复填充现有数据 [英] Drop Down List Repeatedly populate the Existing Data

问题描述

亲爱的朋友





我使用下拉列表时遇到问题。但是代码工作正常，但是当我从下拉列表中选择一个项目并且gridview相应地显示结果但是dropdownlist一次又一次地重复其现有数据时会出现问题。



这是代码 plz 请纠正它

Dear Friend


i have a problem using dropdownlist. however code is working but there is a problem when i select an item from the drop down list and the gridview show the result accordingly but dropdownlist repeats its existing data again and again.

Here is a code plz please rectify it

protected void Page_Load(object sender, EventArgs e)
        {
            string cs = ConfigurationManager.ConnectionStrings["LibraryDatabase"].ToString();
            using (SqlConnection con = new SqlConnection(cs))
            {
                SqlCommand cmd = new SqlCommand("select * from tblBooks  where Title=@TITLE", con);
                cmd.Parameters.AddWithValue("@TITLE", DropDownList1.SelectedValue);
                SqlCommand cmd1 = new SqlCommand("select Title from tblBooks",con);
                
                con.Open();
                SqlDataReader rdr = cmd.ExecuteReader();
                GridView1.DataSource = rdr;
                GridView1.DataBind();
                rdr.Close();
                SqlDataReader rdr1 = cmd1.ExecuteReader();

                while (rdr1.Read() == true)
                {
                    DropDownList1.Items.Add(new ListItem( rdr1["Title"].ToString()));
               }

                rdr1.Close();
            }
        }

推荐答案

试试这段代码

把gridview的这个属性



1. EnableViewState =false

2. AutoPostBack =True

3. AppendDataBoundItems = 真实



然后



以下代码

try this code
put this property of gridview

1. EnableViewState="false"
2. AutoPostBack="True"
3. AppendDataBoundItems="True"

then

following code

protected void Page_Load(object sender, EventArgs e)
{ 
    if(!ispostback)
    {
     
        //put your code here  
    
    }
}

protected void Page_Load(object sender, EventArgs e)
{
    if(!ispostback)
    { 
        //put your code here   
    }
}

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