调用Page_Load函数时，表单变为空白？

Question

我在表格中遇到问题。有两个文本字段，然后有下拉菜单，链接到数据库。

当我点击下拉菜单时，我的两个文本字段变空了。

protected void OnChange_Acdemics(object Sender, EventArgs e)
    {
        DropDownList list = (DropDownList)Sender;
        string value = (string)list.SelectedValue;

        // degrees_dropdown.Visible = true;
        try
        {

            //   String query = "SELECT Degree_types.detail,Degree_Detail.GPA FROM Degree_Detail INNER JOIN Degree_types ON Degree_Detail.Degree_tilte = Degree_types.Degree_title where Degree_types.degree_type = '" + value + "';";
            String query = "Select detail from Degree_Detail where id=" + int.Parse(value) + ";";
            Dt = dbComm.GetDataTable(query);
            Degree_Selection.DataTextField = "detail";
            // Degree_Selection.DataValueField = "GPA";
            Degree_Selection.DataSource = Dt;
            Degree_Selection.DataBind();


        }
        catch (Exception ex)
        {

        }
    }

Answer 1

您需要使用Page.IsPostBack：

来处理此问题

if(!Page.IsPostBack)
{
   // load page 
}
else
{
   // check input values and set it again
}