Question

我只是对如何处理这段代码感到难过，我只是想在我的插入客户表单上实现一个'无重复'的捕获，但它每次都只是通过我的if语句滑到else。这是来源。我也尝试了一个结果相同的.Equals :(

 Protected Sub srcAllClients_Inserting(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.SqlDataSourceCommandEventArgs) Handles srcAllClients.Inserting
        'Establish Variables
        Dim emailAddress As String
        Dim srcUsers As SqlDataSource = New SqlDataSource()

        srcUsers.ConnectionString = ConfigurationManager.ConnectionStrings("ISSD21ConnectionString").ConnectionString

        Dim view As DataView
        view = DirectCast(srcUsers.Select(DataSourceSelectArguments.Empty), DataView)
        srcUsers.SelectCommand = "SELECT EmailAddress FROM ISSDClients"
        srcUsers.DataSourceMode = SqlDataSourceMode.DataReader
        Dim reader As IDataReader
        reader = DirectCast(srcUsers.Select(DataSourceSelectArguments.Empty), IDataReader)

        emailAddress = FormView1.FindControl("txtEmail").ToString

        While reader.Read()
            If reader("EmailAddress") = (emailAddress) Then
                lblError.Text = "Your Email is NOT Unique!"
                'this is where we cancel the update and return an error
            Else
                lblError.Text = "Your Email is Unique!"
                'nothing needs to happen, maybe just tell them that it went through
            End If
        End While

        reader.Close()
    End Sub

Answer 1

emailAddress = FormView1.FindControl("txtEmail").ToString

将返回字符串“System.Web.UI.WebControls.TextBox”。您没有访问保存文本值的控件的实际属性，您只是在控件本身上调用ToString()。

试试这个：

Dim emailBox As TextBox = CType(FormView1.FindControl("txtEmail"), TextBox);
emailAddress = emailBox.Text

Answer 2

除了Womp的回答......

在通过电子邮件记录运行的while循环中，一旦找到匹配的电子邮件并提醒用户，您需要突破循环。

if reader("EmailAddress") = (emailAddress) then
  '1.  Break from the Loop
End if

Answer 3

我建议您将emailAddress作为参数传递给SQL Server。

Select Count(EmailAddress) From ISSDClients
Where EmailAddress = @EmailAddress

使用ExecuteScalar执行此语句并将结果转换为整数。如果结果为零，则表示您没问题，否则会显示错误。

这样做可以避免使用while循环，如果你的表有很多行，它应该快得多。

您还需要从“电子邮件文本”框中获取“文本”属性。

emailAddress = FormView1.FindControl("txtEmail").Text.ToString

Answer 4

您可能需要查看String.Compare方法，这样可以更轻松地进行比较，而不考虑区分大小写和文化。它确实将空格视为字符串的一部分，因此您可能希望在调用字符串之前对其进行修剪，以帮助规范化。

例如，以下字符串将被视为相等：

var firstString  = "some StrinG to Compare  ";
var secondString = "  somE string to COMPARE";

var equal = (String.Compare(firstString.Trim(), secondString.Trim(), StringComparison.InvariantCultureIgnoreCase) == 0);

将数据源中的值与字符串进行比较

4 个答案: