好的,所以我有一个最初从数据库填充的下拉列表 . 现在基于数据表,我希望所选值等于驻留在数据库中的文本 . 无论我做什么,它只显示“---选择一个---”,这是我手动添加到下拉列表项列表中的唯一项目,如果我拉的值为空(或者这就是我想要的那样),则显示默认值去做)
protected void Page_Load(object sender, EventArgs e)
{
Master.TopLabel = "Survey Creation";
if (!IsPostBack)
{
SqlConnection Connection = DatabaseConnection.GetSurveySystemConnection();
string sqlquery = "SELECT S.[Survey_Desc], S.[Start_Date], C.[Category_Name] ,S.[End_Date], S.[Audience] FROM [Survey] S Inner Join Category C On S.Category_ID = C.ID Where S.[ID] =" + Session["Survey_ID"];
SqlCommand cmd = new SqlCommand(sqlquery, Connection);
cmd.CommandType = CommandType.Text;
SqlDataAdapter da = new SqlDataAdapter();
da.SelectCommand = cmd;
DataTable DT = new DataTable();
da.Fill(DT);
if (DT != null)
{
DescriptionMemo.Text = DT.Rows[0]["Survey_Desc"].ToString();
CategoryDropDownList.SelectedIndex = CategoryDropDownList.Items.IndexOf(CategoryDropDownList.Items.FindByText(DT.Rows[0]["Category_Name"].ToString()));
StartDateCalender.SelectedDate = DateTime.Parse(DT.Rows[0]["Start_Date"].ToString());
EndDateCalender.SelectedDate = DateTime.Parse(DT.Rows[0]["End_Date"].ToString());
string Audience = DT.Rows[0]["Audience"].ToString();
if (Audience == "Students Only")
{
AudienceRadioGroup.Items[0].Selected = true;
}
else if (Audience == "Staff Only")
{
AudienceRadioGroup.Items[1].Selected = true;
}
else
{
AudienceRadioGroup.Items[2].Selected = true;
}
}
Connection.Close();
}
}
aspx页面中的DropDownList .
<asp:DropDownList ID="CategoryDropDownList" runat="server"
DataSourceID="SqlDataSource1" DataTextField="Category_Name"
DataValueField="Category_Name" AppendDataBoundItems="true" Height="16px"
Width="200px">
<asp:ListItem>---Select One---</asp:ListItem>
</asp:DropDownList>
sql datasource select命令 .
SELECT [Category_Name] FROM [Category]
编辑:这是完整的代码,但我不知道它是否相关,抱歉 .
3 回答
变化:
至
两件事情:
don 't use a global connection in ASP.NET (at least, don' t使它们成为静态的)因为它是一个多线程环境 . 而是始终使用
using-statement
尽快关闭连接将
if(!IsPostback)
检查放入Page_Load
,当EnableViewState
设置为true
(默认值)时,不要回发数据绑定控件 . 否则将不会触发事件并覆盖值(如DropDownList-SelectedIndex
) .OnPageLoad CategoryDropDownList.Items.FindByText(categoryName).selected = true;