在使用visual basic的文本框中進行驗證

Question

我即將對使用vb的文本框進行驗證。有人可以幫助我如何驗證如果我使用vb語言將文本留空？ N如何驗證角色，電話號碼和電子郵件？

Imports System.Data 
Imports System.Data.SqlClient 
Imports System.IO 
Imports System.Web.UI.WebControls 


Partial Class _Default 
    Inherits System.Web.UI.Page 
    'Dim con As New SqlConnection(ConfigurationManager.ConnectionStrings("dbconnection").ConnectionString)` 


Dim con As New SqlConnection("Data Source=.\SQLEXPRESS;AttachDbFilename=C:\Users\user\Documents\Visual Studio 2010\feedbackScholarInn\App_Data\Database.mdf;Integrated Security=True;User Instance=True") 

     Protected Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button1.Click 
      Dim date1 As Date = Date.Now 
      con.Open() 
      Dim cmd As New SqlCommand("insert into complainer(fullname,no_Tel,email) values(@fullname,@no_Tel,@email)", con) 
      cmd.Parameters.AddWithValue("@fullname", txtFullname.Text) 
      cmd.Parameters.AddWithValue("@no_Tel", txtno_Tel.Text) 
      cmd.Parameters.AddWithValue("@email", txtEmail.Text) 
      cmd.ExecuteNonQuery() 
      con.Close() 

      con.Open() 
      Dim cmd2 As New SqlCommand("insert into feedbackDetails(message,subject,status,typeofFeedback,date,roomNo) values(@message,@subject,@status,@typeofFeedback,@date,@roomNo)", con) 
      cmd2.Parameters.AddWithValue("@message", txtMessage.Text) 
      cmd2.Parameters.AddWithValue("@status", "New") 
      cmd2.Parameters.AddWithValue("@subject", txtSubject.Text) 
      cmd2.Parameters.AddWithValue("@typeofFeedback", dropDownFeedback.SelectedValue) 
      cmd2.Parameters.AddWithValue("@date", date1) 
      cmd2.Parameters.AddWithValue("@roomNo", txtRoom.Text) 
      cmd2.ExecuteNonQuery() 


      con.Close() 


     End Sub 
    End Class 

Answer 1

空文本，您可以使用離開事件，但我更喜歡KeyUp事件上的文本框：

Private Sub txtFullname_Leave(sender As Object, e As KeyEventArgs) Handles txtFullname.Leave 
    If txtFullname.Text.Length < 1 Then 
     MessageBox("Please enter a text !") 
    End If 
End Sub 

Private Sub txtEmail_Leave(sender As Object, e As KeyEventArgs) Handles txtEmail.Leave 
    IsEmail(txtEmail.text) 
End Sub 

的電話沒有驗證閱讀：https://stackoverflow.com/a/24895684/2269262
「的電話確認有differend驗證按國家格式
「你也可以這樣說的：https://msdn.microsoft.com/en-us/library/system.net.mail.mailaddress.aspx

Function IsEmail(Byval email as string) as boolean 
    Static emailExpression As New Regex("^[_a-z0-9-]+(.[a-z0-9-]+)@[a-z0-9-]+(.[a-z0-9-]+)*(.[a-z]{2,4})$") 
    return emailExpression.IsMatch(email) 
End Function