不允许从数据类型sql_variant隐式转换为varbinary（max）。 使用CONVERT函数运行此查询。 ASP.NET SQL数据源

Question

Although, there are a lot of questions with this title, but mine is different.

I am using a ASP.NET ListView bound to a sql datasource control & as such have not added any conversions. Also I am sending DBNull value in ListView's Inserting Event.

The DataSource Code:

  <asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="<%$ ConnectionStrings:Main %>"  InsertCommand="pInsert" InsertCommandType="StoredProcedure" 
    SelectCommand="pGet" SelectCommandType="StoredProcedure"   >
            <DeleteParameters>
                <asp:Parameter Name="Code" Type="Int32" />
            </DeleteParameters>
            <InsertParameters>
                <asp:SessionParameter Name="SubscriptionCode" SessionField="EntryCode" Type="Int32" DefaultValue="-1" />
                <asp:Parameter Name="Attachment" Type="Object" />

            </InsertParameters>
            <SelectParameters>                
                <asp:SessionParameter Name="SubscriptionCode" SessionField="EntryCode" Type="Int32" DefaultValue="-1" />
                <asp:Parameter DefaultValue="false" Name="ForEdit" Type="Boolean" />
            </SelectParameters>           
        </asp:SqlDataSource>

The Code Behind :

protected void lv_ItemInserting(object sender, ListViewInsertEventArgs e)
        {           
            e.Values["Attachment"] = DBNull.Value;
        }   

I have also tried removing the Type="Object" property as specified here

Answer 1

Remove the Type="Object" property from this line <asp:Parameter Name="Attachment" Type="Object" /> and try this in code behind :

protected void lv_ItemInserting(object sender, ListViewInsertEventArgs e)
{
   e.Values["Attachment"] = System.Data.SqlTypes.SqlBinary.Null;
}

Answer 2

Here is another solution. Just try the code below.

The DataSource Code :

<asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="<%$ ConnectionStrings:Main %>"  InsertCommand="pInsert" InsertCommandType="StoredProcedure" 
SelectCommand="pGet" SelectCommandType="StoredProcedure"   >
    <DeleteParameters>
        <asp:Parameter Name="Code" Type="Int32" />
    </DeleteParameters>
    <InsertParameters>
        <asp:SessionParameter Name="SubscriptionCode" SessionField="EntryCode" Type="Int32" DefaultValue="-1" />
        <asp:Parameter Name="Attachment" />

    </InsertParameters>
    <SelectParameters>                
        <asp:SessionParameter Name="SubscriptionCode" SessionField="EntryCode" Type="Int32" DefaultValue="-1" />
        <asp:Parameter DefaultValue="false" Name="ForEdit" Type="Boolean" />
    </SelectParameters>           
</asp:SqlDataSource>

The Code Behind :

protected void lv_ItemInserting(object sender, ListViewInsertEventArgs e)
{
   e.Values["Attachment"] = -1;
}