How can I find out if a variable has a value?

zhouji700

Then you always have the definition and assignment of theTitle, set a breakpoint at that assignment

板砖飞校长

I defined it in <script> </ script>:

<asp: Content ID = "Content1" ContentPlaceHolderID = "ContentPlaceHolder1" Runat = "Server">

  <script Runat = "Server">
      Dim theTitle As String
      Dim theContent As String
      Dim theAuthor As String
      Dim theCopyFrom As String
      Dim theAddTime As String
      Sub page_load (ByVal Sender As Object, ByVal E As EventArgs)
          

          Dim Cnn As SqlConnection
          Dim Cmd As SqlCommand
          Dim DataR As SqlDataReader
          Dim StrCnn As String
         
          Dim codestr As String = Request.QueryString ("id")
          Dim sql As String
          If Trim (codestr) <> "" Then
              StrCnn = "server = localhost; uid = as; pwd =; database = myweb"
              Cnn = New SqlConnection (StrCnn)
              Cnn.Open ()
              sql = "select * from book_info where id ="&Trim (codestr)
              Cmd = New SqlCommand (sql, Cnn)
              DataR = Cmd.ExecuteReader
              If DataR.Read () Then
                  theTitle = DataR ("title")
                  theContent = DataR ("content")
                  theAuthor = DataR ("author")
                  theCopyFrom = DataR ("copyfrom")
                  theAddTime = DataR ("addtime")
              Else
                  Cnn.Close ()
                  Response.Write ("<font color = 'gray'> Please select an article! </ Font>")
                  Response.End ()
              End If
              Cnn.Close ()
          End If
      End Sub
</ script>
----
I set a breakpoint, but page_load is not executed, why?

zhouji700

Try to change to the following:

If Trim (codestr) <> "" Then
    StrCnn = "server = localhost; uid = as; pwd =; database = myweb"
    Cnn = New SqlConnection (StrCnn)
    Cnn.Open ()
    sql = "select * from book_info where id ="&Trim (codestr)
    Cmd = New SqlCommand (sql, Cnn)
    DataR = Cmd.ExecuteReader
    If DataR.Read () Then
        theTitle = DataR ("title")
  Response.Write ("TheTitle sets the value")
  Response.End ()
        theContent = DataR ("content")
        theAuthor = DataR ("author")
        theCopyFrom = DataR ("copyfrom")
        theAddTime = DataR ("addtime")
    Else
  Response.Write ("theTitle has no set value")
  Response.End ()
        Cnn.Close ()
        Response.Write ("<font color = 'gray'> Please select an article! </ Font>")
        Response.End ()
    End If
    Cnn.Close ()
Else
  Response.Write ("theTitle has no set value")
  Response.End ()
End If