c# - 如何从下拉列表框中获取值

Question

我想要的是从下拉列表中的所选项目中获取值，并使用它在按钮单击事件中进行查询(选择表格)。

    protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
    {
        if (DropDownList1.SelectedIndex == 1)
        {
            using (SqlConnection con = new SqlConnection(DBcon))
            {

               SqlCommand sqlCommand = new SqlCommand("Select * from tbl_WinApps_FileHeader");
               sqlCommand.Connection = con;

               SqlDataReader read = sqlCommand.ExecuteReader();

                GridView1.DataSource = read;
                GridView1.DataBind();


            }
        }
    }

  <asp:DropDownList ID="DropDownList1" runat="server" 
        onselectedindexchanged="DropDownList1_SelectedIndexChanged">
        <asp:ListItem>ER00 - File Header</asp:ListItem>
        <asp:ListItem>ER01 - Expense Report Trans</asp:ListItem>
        <asp:ListItem>ER02 - Expense Report Item Trans</asp:ListItem>
        <asp:ListItem>ER03 - Expense Report Item Tax Trans</asp:ListItem>
        <asp:ListItem>ER04 - Expense Report Item</asp:ListItem>
    </asp:DropDownList>

Answer 1

DropDownList1.SelectedValue.ToString();

或者

DropDownList1.Text;

或者

DropDownList1.SelectedValue.ToString();