如何处理 Web 应用程序中 asp.net“违反唯一键约束”异常
本文关键字：唯一 一键 异常 约束 net asp 何处理 处理 应用程序 Web | 更新日期: 2023-09-27 17:55:56
<AlternatingRowStyle BackColor="#F7F7F7" HorizontalAlign="Justify" Wrap="False" />
<Columns>
<asp:CommandField ShowDeleteButton="True" ButtonType="Image" />
<asp:CommandField ShowEditButton ="True" ButtonType="Image" />
<asp:TemplateField HeaderText="Name" SortExpression="Name">
<EditItemTemplate>
<asp:TextBox ID="TextBox1" runat="server" Text='<%# Bind("Name") %>'></asp:TextBox>
</EditItemTemplate>
<ItemTemplate>
<asp:Label ID="Label1" runat="server" Text='<%# Bind("Name") %>'></asp:Label>
</ItemTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="Email" SortExpression="Email">
<EditItemTemplate>
<asp:TextBox ID="TextBox2" runat="server" Text='<%# Bind("Email") %>'></asp:TextBox>
</EditItemTemplate>
<ItemTemplate>
<asp:Label ID="Label2" runat="server" Text='<%# Bind("Email") %>'></asp:Label>
</ItemTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="Occupation" SortExpression="Occupation">
<EditItemTemplate>
<asp:TextBox ID="TextBox3" runat="server" Text='<%# Bind("Occupation") %>'></asp:TextBox>
</EditItemTemplate>
<ItemTemplate>
<asp:Label ID="Label3" runat="server" Text='<%# Bind("Occupation") %>'></asp:Label>
</ItemTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="Role" SortExpression="Role">
<EditItemTemplate>
<asp:DropdownList ID="Roles" runat="server" Text='<%# Bind("Roles") %>'>
<asp:ListItem Selected="True" Text="User" value="User"></asp:ListItem>
<asp:ListItem Selected="False" Text="Admin" value="Admin"></asp:ListItem>
</asp:DropdownList>
</EditItemTemplate>
<ItemTemplate>
<asp:Label ID="Label7" runat="server" Text='<%# Bind("Roles") %>'></asp:Label>
</ItemTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="Address" SortExpression="Address">
<EditItemTemplate>
<asp:TextBox ID="TextBox4" runat="server" Text='<%# Bind("Address") %>'></asp:TextBox>
</EditItemTemplate>
<ItemTemplate>
<asp:Label ID="Label4" runat="server" Text='<%# Bind("Address") %>'></asp:Label>
</ItemTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="Mobile" SortExpression="Mobile">
<EditItemTemplate>
<asp:TextBox ID="TextBox5" runat="server" Text='<%# Bind("Mobile") %>'></asp:TextBox>
</EditItemTemplate>
<ItemTemplate>
<asp:Label ID="Label5" runat="server" Text='<%# Bind("Mobile") %>'></asp:Label>
</ItemTemplate>
</asp:TemplateField>
</Columns>
<EditRowStyle HorizontalAlign="Center" Wrap="False" />
<FooterStyle BackColor="#B5C7DE" ForeColor="#4A3C8C" />
<HeaderStyle BackColor="#4A3C8C" Font-Bold="True" ForeColor="#F7F7F7" />
<PagerStyle BackColor="#E7E7FF" ForeColor="#4A3C8C" HorizontalAlign="Right" />
<RowStyle BackColor="#E7E7FF" ForeColor="#4A3C8C" />
<SelectedRowStyle BackColor="#738A9C" Font-Bold="True" ForeColor="#F7F7F7" />
<SortedAscendingCellStyle BackColor="#F4F4FD" />
<SortedAscendingHeaderStyle BackColor="#5A4C9D" />
<SortedDescendingCellStyle BackColor="#D8D8F0" />
<SortedDescendingHeaderStyle BackColor="#3E3277" />
</asp:GridView>
<asp:SqlDataSource ID="SqlDataSource1" runat="server"
ConnectionString="<%$ ConnectionStrings:UsTravelConnectionString %>"
DeleteCommand="DELETE FROM [Users] WHERE [Id] = @Id"
InsertCommand="INSERT INTO [Users] ([Name], [Email], [Occupation],[Roles], [Address], [Mobile]) VALUES (@Name, @Email, @Occupation,@Roles, @Address, @Mobile)"
SelectCommand="SELECT [Name], [Email], [Occupation],[Roles], [Address], [Mobile], [Id] FROM [Users]"
UpdateCommand="UPDATE [Users] SET [Name] = @Name, [Email] = @Email, [Occupation] = @Occupation, [Roles]=@Roles, [Address] = @Address, [Mobile] = @Mobile WHERE [Id] = @Id">
<DeleteParameters>
<asp:Parameter Name="Id" Type="Int32" />
</DeleteParameters>
<InsertParameters>
<asp:Parameter Name="Name" Type="String" />
<asp:Parameter Name="Email" Type="String" />
<asp:Parameter Name="Occupation" Type="String" />
<asp:Parameter Name="Roles" Type="String" />
<asp:Parameter Name="Address" Type="String" />
<asp:Parameter Name="Mobile" Type="String" />
</InsertParameters>
<UpdateParameters>
<asp:Parameter Name="Name" Type="String" />
<asp:Parameter Name="Email" Type="String" />
<asp:Parameter Name="Occupation" Type="String" />
<asp:Parameter Name="Roles" Type="String" />
<asp:Parameter Name="Address" Type="String" />
<asp:Parameter Name="Mobile" Type="String" />
<asp:Parameter Name="Id" Type="Int32" />
</UpdateParameters>
</asp:SqlDataSource>
<br />
<p runat="server" id="noRowsMsg" sytle="display:none"></p>
</form>
电子邮件字段在表中具有唯一的键约束。 我在处理异常和输出用户友好的消息时遇到困难，该消息通知在更新电子邮件时更新新EmailID。
一种可能的方法是在"插入单击"和实际的数据库插入操作之间引入验证。
可以通过向 Sql 数据源添加插入事件处理程序来执行此操作。
OnInserting="SqlDataSource_Inserting"
完成此操作后，将处理程序定义为：
protected void SqlDataSource_Inserting(object sender, SqlDataSourceCommandEventArgs e)
{
var emailToBeInserter = e.Command.Parameters["@Email"].Value;
// do a DB lookup call and validate if it is unique.
// if not unique, cancel the Insert and display an error message.
e.Cancel = true; // if email already exists in DB.
// if unique, do nothing.
}
执行显式验证具有额外数据库调用的成本，但通常比让"INSERT"逻辑运行并抛出"唯一键"和其他此类异常更好。