ASP.NET中F5刷新按键数据插入两次的问题
利用服务器控件做的页面，刷新按钮一按，客户端会把View中的数据重新送到服务器端，从而造成数据插入两次的问题。
解决方案利用服务器端的session和客户端的ViewState中保存的数据是否不同来判定。
<%@ Page Language="VB" Strict="True" %>
<%@ Import Namespace="System.Data" %><%@ Import Namespace="System.Data.SqlClient" %><script runat="server">
Sub Page_Load (sender As Object, e As EventArgs) If Not Page.IsPostBack then Session("AddTime") = Server.URLEncode(System.DateTime.Now.ToString()) End IfEnd SubSub Page_PreRender (sender As Object, e As EventArgs) ViewState("AddTime") = Session("AddTime")End SubSub Button1_Click(sender As Object, e As EventArgs) If Session("AddTime").ToString() = ViewState("AddTime").ToString() Then If AddEmployee(firstName.Text, lastName.Text) = 0 Message.Text = "Success" Session("AddTime") = Server.URLEncode(System.DateTime.Now.ToString()) Else Message.Text = "Failure - - Database" End If Else Message.Text = "Failure - Session" End IfEnd SubFunction AddEmployee(firstName As String, lastName As String) As Integer Dim connectionString As String = "server='(local)'; trusted_connection=true; database='Northwind'" Dim dbConnection As New SqlConnection(connectionString) Dim insertString As String = "INSERT INTO Employees (FirstName, LastName) VALUES (@FirstName, @LastName)" Dim dbCommand As New SqlCommand dbCommand.CommandText = insertString dbCommand.Connection = dbConnection dbCommand.Parameters.Add(New SqlParameter("@FirstName",SqlDbType.NVarchar,10)) dbCommand.Parameters("@FirstName").Value = firstName dbCommand.Parameters.Add(New SqlParameter("@LastName",SqlDbType.NVarchar,20)) dbCommand.Parameters("@LastName").Value = lastName Dim rowsAffected As Integer = 0 Dim commandResult As Integer = 1 Try dbConnection.Open rowsAffected = dbCommand.ExecuteNonQuery If rowsAffected > 0 Then commandResult = 0 Catch ex AS SqlException commandResult = ex.Number Finally dbConnection.Close End Try Return commandResult
End Function
</script><html><head> <title>Preventing Duplicate Record Insertion on Page Refresh - Using a Session and ViewState Variables</title></head><body> <form runat="server"> <p>First Name <asp:TextBox id="firstName" runat="server" /> <p>Last Name <asp:TextBox id="lastName" runat="server" /> <p><asp:Button id="Button1" onclick="Button1_Click" runat="server" Text="Add Employee" /> <p><asp:Label id="Message" runat="server" /> <input id="hiddenSession" type="hidden" runat="server" /> </form></body></html>