在当前行的下拉列表中选择新值时，不会更新 Gridview 数据库

我有一个有四列的网格视图。前三个是绑定字段（STARTENDYEAR，ENDYEAR和IDENTIFIER），第三个是下拉列表（CHANGE）。下拉列表的目的是更改标识符字段的值。前三列从一个预言机表中获取。每个 STARTENDYEAR 都有一个适用于它的标识符值列表。这些适用值在不同的表中可用。这些值已成功提取并填充到下拉列表中。我正在将 ASP.NET 与 C# 一起使用

要求：每当用户从下拉列表中选择不同的值时，都需要使用新的标识符值更新网格视图和后端表。

到目前为止已实现：下拉列表已填充第二个表中适用值的列表。每当用户选择新值时，我都可以在后端代码中捕获新值。

问题：无法使用提取的新标识符值更新网格视图和数据库。我怀疑这可能是一个数据绑定问题，它阻止了 sql 更新查询在后端 C# 代码上成功触发。

ASP 代码：

<%@ Page Title="Database" Language="C#" MasterPageFile="~/Site.master"    AutoEventWireup="true"
CodeFile="Database.aspx.cs" Inherits="About" %>
 <asp:Content ID="HeaderContent" runat="server" ContentPlaceHolderID="HeadContent">
 </asp:Content>
 <asp:Content ID="BodyContent" runat="server" ContentPlaceHolderID="MainContent">
 <asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False"
 DataSourceID="SqlDataSource2" onrowdatabound="GridView1_RowDataBound1" DataKeyNames="IDENTIFIER">
        <Columns>
             <asp:BoundField DataField="STARTENDYEAR" HeaderText="STARTENDYEAR" 
                SortExpression="STARTENDYEAR" />
            <asp:BoundField DataField="ENDYEAR" HeaderText="ENDYEAR" SortExpression="ENDYEAR" />
            <asp:BoundField DataField="IDENTIFIER" HeaderText="IDENTIFIER" 
                SortExpression="IDENTIFIER" />
            <asp:TemplateField HeaderText="CHANGE" SortExpression="CHANGE"> 
                <ItemTemplate> 
                    <asp:DropDownList ID="DropDownList1" runat="server" DataTextField="CODE" DataValueField="CODE" 
                    OnSelectedIndexChanged="DropDownList_SelectedIndexChanged" AutoPostBack="True"> 
                    </asp:DropDownList> 
                </ItemTemplate> 
            </asp:TemplateField> 
        </Columns>
    </asp:GridView>
     <asp:SqlDataSource ID="SqlDataSource2" runat="server" 
        ConnectionString="<%$ ConnectionStrings:RonSql %>" 
        ProviderName="<%$ ConnectionStrings:RonSql.ProviderName %>"
    SelectCommand="select STARTENDYEAR, ENDYEAR, IDENTIFIER from R70A109 where (STATE = :SegState) order by STARTENDYEAR, ENDYEAR">
         <SelectParameters>
            <asp:SessionParameter Name="SegState" SessionField="SegState" DefaultValue="0" />
         </SelectParameters>               

    </asp:SqlDataSource>
    <asp:SqlDataSource ID="SqlDataSource1" runat="server" 
        ConnectionString="<%$ ConnectionStrings:RonSql %>" 
        ProviderName="<%$ ConnectionStrings:RonSql.ProviderName %>"> 

    </asp:SqlDataSource>

C# 代码：

public partial class About : System.Web.UI.Page
{
        protected void GridView1_RowDataBound1(object sender, GridViewRowEventArgs e)
        {          DataRowView CurrentRow = (DataRowView)e.Row.DataItem;
         if (e.Row.RowType == DataControlRowType.DataRow)
         {
             int StartYear = Convert.ToInt32(CurrentRow["StartYear"].ToString());
        if (StartYear > 2005)
            StartYear = 2005;
            DataTable dtcodes = GetByState(StartYear);
            DropDownList CurrentDropDown = (DropDownList)e.Row.FindControl("DropDownList1");
            CurrentDropDown.DataSource = dtcodes;
            CurrentDropDown.DataBind();
    }
}


 protected void DropDownList_SelectedIndexChanged(object sender, EventArgs e)
{
   DropDownList SelectedDropDown = (DropDownList)sender;
   GridViewRow SelectedRow = (GridViewRow)SelectedDropDown.NamingContainer;
   int StartYear = Convert.ToInt32(SelectedRow.Cells[0].Text);
   int EndYear = Convert.ToInt32(SelectedRow.Cells[1].Text);
   int IdentifierOld = Convert.ToInt32(SelectedRow.Cells[2].Text);
   int IdentifierNew =  Convert.ToInt32(SelectedDropDown.SelectedItem.Value);

   if (StartYear < 2005)
   {
       string ConString = "Data Source=ORACLE;User ID=****;Password=****";
       string CodeUpdate = "update R70A109 set IDENTIFIER = :New_Identifier where StartYear = :StartYear) AND (EndYear = :EndYear) AND (IDENTIFIER = :Old_Identifier)";
       OracleConnection con = new OracleConnection(ConString);
       con.Open();
       OracleCommand SqlCodeUpdate = new OracleCommand(CodeUpdate, con);
       SqlCodeUpdate.Parameters.Add(new OracleParameter("@New_Identifier", IdentifierNew));
       SqlCodeUpdate.Parameters.Add(new OracleParameter("@StartYear", StartYear));
       SqlCodeUpdate.Parameters.Add(new OracleParameter("@EndYear", EndYear));
       SqlCodeUpdate.Parameters.Add(new OracleParameter("@Old_Identifier", IdentifierOld));
       OracleDataAdapter DatAdpt = new OracleDataAdapter();
       DatAdpt.UpdateCommand = SqlCodeUpdate;
        con.Close();
    }
}

}

if (StartYear < 2005)
   {
       string ConString = "Data Source=ORACLE;User ID=****;Password=****";
       string CodeUpdate = "update R70A109 set IDENTIFIER = :New_Identifier where StartYear = :StartYear) AND (EndYear = :EndYear) AND (IDENTIFIER = :Old_Identifier)";
       using (OracleConnection con = new OracleConnection(ConString))
       {
            OracleCommand SqlCodeUpdate = new OracleCommand(CodeUpdate, con);
            SqlCodeUpdate.Parameters.Add(new OracleParameter("@New_Identifier", IdentifierNew));
            SqlCodeUpdate.Parameters.Add(new OracleParameter("@StartYear", StartYear));
            SqlCodeUpdate.Parameters.Add(new OracleParameter("@EndYear", EndYear));
            SqlCodeUpdate.Parameters.Add(new OracleParameter("@Old_Identifier", IdentifierOld));
            SqlCodeUpdate.Connection.Open();
            SqlCodeUpdate.ExecuteNonQuery();
       }
    }
...