Question

我使用的是System.Data.EntityClient而不是简单的System.Data.SqlClient

我是实体框架的新手，所以请原谅我的无知，请不要提供神秘的回复，因为我没有必要的背景信息来理解它们。

我做了几个小时的研究，找不到解决问题的正确答案组合。

问题：

当＆＃34;删除＆＃34;触发事件页面抛出此错误：

DELETE语句与REFERENCE约束冲突

我想捕获该错误，然后在页面上填写一个标签

此客户无法删除

我的ASP页面：

<asp:Content ID="Content2" ContentPlaceHolderID="ContentPlaceHolder1" runat="server">
<p>
    <asp:DetailsView ID="CustomerDetail" runat="server" 
        DataSourceID="CustomerSqlDataSource" Height="50px" 
        Width="215px" Visible="False" AutoGenerateRows="False" 
        OnModeChanged="CustomerDetail_ModeChanged">
        <Fields>
            <asp:BoundField DataField="FirstName" HeaderText="First Name:" />
            <asp:BoundField DataField="LastName" HeaderText="Last Name:" />
            <asp:BoundField DataField="City" HeaderText="City:" />
            <asp:BoundField DataField="State" HeaderText="State" />
            <asp:CommandField ShowInsertButton="True" />
        </Fields>
    </asp:DetailsView>
</p>
<asp:Button ID="NewCustomerButton" runat="server" Text="New Customer" OnClick="NewCustomerButton_Click" />
<p>
    <asp:Label ID="DeleteLabel" runat="server" Text="" Visible="false"/>
    <asp:GridView ID="CustomerGrid" runat="server" AutoGenerateColumns="False" 
        DataKeyNames="CustomerId" DataSourceID="CustomerSqlDataSource" 
        OnSelectedIndexChanged="CustomerGrid_SelectedIndexChanged" >
        <Columns>
            <asp:CommandField ShowDeleteButton="True" ShowEditButton="True" />
            <asp:BoundField DataField="FirstName" HeaderText="FirstName" SortExpression="FirstName" />
            <asp:BoundField DataField="LastName" HeaderText="LastName" SortExpression="LastName" />
            <asp:BoundField DataField="City" HeaderText="City" SortExpression="City" />
            <asp:BoundField DataField="State" HeaderText="State" SortExpression="State" />
        </Columns>
    </asp:GridView>
    <br />

    <br />
    <asp:SqlDataSource ID="CustomerSqlDataSource" runat="server" 
        ConnectionString="<%$ ConnectionStrings:ITP236-InventoryConnectionString %>" 
        DeleteCommand="DELETE FROM [Customer] WHERE [CustomerId] = @CustomerId" 
        InsertCommand="INSERT INTO [Customer] ([FirstName], [LastName], [City], [State]) 
                        VALUES (@FirstName, @LastName, @City, @State)" 
        SelectCommand="SELECT [CustomerId], [FirstName], [LastName], [City], [State] FROM [Customer]" 
        UpdateCommand="UPDATE [Customer] 
                        SET [FirstName] = @FirstName, [LastName] = @LastName, [City] = @City, [State] = @State 
                        WHERE [CustomerId] = @CustomerId" OnDeleted="CustomerSqlDataSource_Deleted">
        <DeleteParameters>
            <asp:Parameter Name="CustomerId" Type="Int32" />
        </DeleteParameters>
        <InsertParameters>
            <asp:Parameter Name="FirstName" Type="String" />
            <asp:Parameter Name="LastName" Type="String" />
            <asp:Parameter Name="City" Type="String" />
            <asp:Parameter Name="State" Type="String" />
        </InsertParameters>
        <UpdateParameters>
            <asp:Parameter Name="FirstName" Type="String" />
            <asp:Parameter Name="LastName" Type="String" />
            <asp:Parameter Name="City" Type="String" />
            <asp:Parameter Name="State" Type="String" />
            <asp:Parameter Name="CustomerId" Type="Int32" />
        </UpdateParameters>
    </asp:SqlDataSource>

</p>

背后的代码不起作用：

protected void CustomerSqlDataSource_Deleted(object sender, SqlDataSourceStatusEventArgs e)
{
     if (e.ExceptionHandled == false)
     {
      e.Command.Cancel();
      DeleteLabel.Visible = true;
      DeleteLabel.Text = "This Customer cannot be deleted";
     }
}

=============================================== ===============================

美国东部时间上午11:41编辑，包含整个错误。虽然，我明白问题是什么，我只是试图在显示之前捕获此错误并将其恢复页面上的标签，标签上写着＆＃34;客户无法删除＆＃34;

=============================================== =============================== ＆＃39; /＆＃39;中的服务器错误应用

DELETE语句与REFERENCE约束冲突＆＃34; FK_SalesOrder_Customer＆＃34;。冲突发生在数据库＆＃34; ITP236-Inventory＆＃34;，table＆＃34; dbo.SalesOrder＆＃34;，column＆＃39; CustomerId＆＃39;中。声明已经终止。

描述：执行当前Web请求期间发生了未处理的异常。请查看堆栈跟踪以获取有关错误及其源自代码的位置的更多信息。

异常详细信息：System.Data.SqlClient.SqlException：DELETE语句与REFERENCE约束冲突＆＃34; FK_SalesOrder_Customer＆＃34;。冲突发生在数据库＆＃34; ITP236-Inventory＆＃34;，table＆＃34; dbo.SalesOrder＆＃34;，column＆＃39; CustomerId＆＃39;中。声明已经终止。

来源错误：

在执行当前Web请求期间生成了未处理的异常。可以使用下面的异常堆栈跟踪来识别有关异常的起源和位置的信息。

堆栈追踪：

[SqlException（0x80131904）：DELETE语句与REFERENCE约束冲突＆＃34; FK_SalesOrder_Customer＆＃34;。冲突发生在数据库＆＃34; ITP236-Inventory＆＃34;，table＆＃34; dbo.SalesOrder＆＃34;，column＆＃39; CustomerId＆＃39;中。该语句已终止。] System.Data.SqlClient.SqlConnection.OnError（SqlException异常，Boolean breakConnection，Action 1 wrapCloseInAction) +1767866 System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection, Action 1 wrapCloseInAction）+5352418 System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning（TdsParserStateObject stateObj，Boolean callerHasConnectionLock，Boolean asyncClose）+244 System.Data.SqlClient.TdsParser.TryRun（RunBehavior runBehavior，SqlCommand cmdHandler，SqlDataReader dataStream，BulkCopySimpleResultSet bulkCopyHandler，TdsParserStateObject stateObj，Boolean＆amp; dataReady）+1691 System.Data.SqlClient.SqlCommand.FinishExecuteReader（SqlDataReader ds，RunBehavior runBehavior，String resetOptionsString）+269 System.Data.SqlClient.SqlCommand.RunExecuteReaderTds（CommandBehavior cmdBehavior，RunBehavior runBehavior，Boolean returnStream，Boolean async，Int32 timeout，Task＆amp; task，Boolean asyncWrite，SqlDataReader ds）+1406 System.Data.SqlClient.SqlCommand.RunExecuteReader（CommandBehavior cmdBehavior，RunBehavior runBehavior，Boolean returnStream，String method，TaskCompletionSource 1 completion, Int32 timeout, Task& task, Boolean asyncWrite) +177 System.Data.SqlClient.SqlCommand.InternalExecuteNonQuery(TaskCompletionSource 1 completion，String methodName，Boolean sendToPipe，Int32 timeout，Boolean asyncWrite）+205 System.Data.SqlClient.SqlCommand.ExecuteNonQuery（）+160 System.Web.UI.WebControls.SqlDataSourceView.ExecuteDbCommand（DbCommand命令，DataSourceOperation操作）+380 System.Web.UI.WebControls.SqlDataSourceView.ExecuteDelete（IDictionary keys，IDictionary oldValues）+568 System.Web.UI.DataSourceView.Delete（IDictionary keys，IDictionary oldValues，DataSourceViewOperationCallback回调）+84 System.Web.UI.WebControls.GridView.HandleDelete（GridViewRow row，Int32 rowIndex）+930 System.Web.UI.WebControls.GridView.HandleEvent（EventArgs e，Boolean causeValidation，String validationGroup）+974 System.Web.UI.WebControls.GridView.RaisePostBackEvent（String eventArgument）+205 System.Web.UI.WebControls.GridView.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent（String eventArgument）+13 System.Web.UI.Page.RaisePostBackEvent（IPostBackEventHandler sourceControl，String eventArgument）+13 System.Web.UI.Page.RaisePostBackEvent（NameValueCollection postData）+9671830 System.Web.UI.Page.ProcessRequestMain（Boolean includeStagesBeforeAsyncPoint，Boolean includeStagesAfterAsyncPoint）+1724

版本信息：Microsoft .NET Framework版本：4.0.30319; ASP.NET版本：4.0.30319.34237

Answer 1

您收到的错误是由于违反了外键约束。 Customer表的主键在某个其他表的外键约束中引用。您无法删除客户，因为其他一些表取决于客户。

例如，如果Orders表中有CustomerId列引用了您尝试删除的客户，该怎么办？客户订购产品，因此订单无法在没有客户的情况下存在。在这种情况下，请尝试更改DELETE语句：

DELETE FROM [Customer] WHERE [CustomerId] = @CustomerId
AND NOT EXISTS (SELECT * FROM [Orders] AS o WHERE o.[CustomerId]=@CustomerId)

这样可以防止删除有订单的客户。您可以在Deleted事件中处理此问题，如下所示：

protected void CustomerSqlDataSource_Deleted(object sender, SqlDataSourceStatusEventArgs e)
{
    if (e.AffectedRows == 0)
    {
        DeleteLabel.Visible = true;
        DeleteLabel.Text = "This Customer cannot be deleted because it has orders";
    }
}

您可以通过选中e.Exception != null代替e.ExceptionHandled == false来处理异常。

Answer 2

protected void CustomerSqlDataSource_Deleted(object sender, SqlDataSourceStatusEventArgs e)
{
     try {
         if (e.ExceptionHandled == false)
         {
         e.Command.Cancel();
         DeleteLabel.Visible = true;
         DeleteLabel.Text = "This Customer cannot be deleted";
     }
     catch {
       // do your thing here when error occurs
     }
}

取消＆＃34;删除＆＃34; event if＆＃34; DELETE语句与REFERENCE约束冲突＆＃34;

2 个答案: