程序一到mrc.eof就出现错误"对象变量未设置或With块变量未设置"不知道为什么
最近买了一本书,书中的例子学生信息管理系统,书买来时附带一张光盘,是原码文件才用ADO连接,按书中说的把文件考到查询分析器中建立数据结构就可运行程序可是一到mrc.eof判断语句就出现错误原码如下:
公共模块代码为:
Public fMainForm As frmMain
Public UserName As String
Sub Main()
Dim fLogin As New frmLogin
fLogin.Show vbModal
If Not fLogin.OK Then
'Login Failed so exit app
End
End If
Unload fLogin
Set fMainForm = New frmMain
fMainForm.Show
End Sub
Public Function ConnectString() _
As String
'returns a DB ConnectString
ConnectString = "FileDSN=studentinfo.dsn;UID=sa;PWD="
End Function
Public Function ExecuteSQL(ByVal SQL _
As String, MsgString As String) _
As ADODB.Recordset
'executes SQL and returns Recordset
Dim cnn As ADODB.Connection
Dim rst As ADODB.Recordset
Dim sTokens() As String
On Error GoTo ExecuteSQL_Error
sTokens = Split(SQL)
Set cnn = New ADODB.Connection
cnn.Open ConnectString
If InStr("INSERT,DELETE,UPDATE", _
UCase$(sTokens(0))) Then
cnn.Execute SQL
MsgString = sTokens(0) & _
" query successful"
Else
Set rst = New ADODB.Recordset
rst.Open Trim$(SQL), cnn, _
adOpenKeyset, _
adLockOptimistic
'rst.MoveLast 'get RecordCount
Set ExecuteSQL = rst
MsgString = "查询到" & rst.RecordCount & _
" 条记录 "
End If
ExecuteSQL_Exit:
Set rst = Nothing
Set cnn = Nothing
Exit Function
ExecuteSQL_Error:
MsgString = "查询错误: " & _
Err.Description
Resume ExecuteSQL_Exit
End Function
Public Function Testtxt(txt As String) As Boolean
If Trim(txt) = "" Then
Testtxt = False
Else
Testtxt = True
End If
End Function
frmlogin窗体原码
Option Explicit
Private Declare Function GetUserName Lib "advapi32.dll" Alias "GetUserNameA" (ByVal lpbuffer As String, nSize As
Long) As Long
Public OK As Boolean
'记录确定次数
Dim miCount As Integer
Private Sub Form_Load()
Dim sBuffer As String
Dim lSize As Long
sBuffer = Space$(255)
lSize = Len(sBuffer)
Call GetUserName(sBuffer, lSize)
If lSize > 0 Then
txtUserName.Text = ""
Else
txtUserName.Text = vbNullString
End If
OK = False
miCount = 0
End Sub
Private Sub cmdCancel_Click()
OK = False
Me.Hide
End Sub
Private Sub cmdOK_Click()
Dim txtSQL As String
Dim mrc As ADODB.Recordset
Dim MsgText As String
'ToDo: create test for correct password
'check for correct password
UserName = ""
If Trim(txtUserName.Text = "") Then
MsgBox "没有这个用户,请重新输入用户名!", vbOKOnly + vbExclamation, "警告"
txtUserName.SetFocus
Else
txtSQL = "select * from user_Info where user_ID = '" & txtUserName.Text & "'"
Set mrc = ExecuteSQL(txtSQL, MsgText)
If mrc.EOF = True Then (就在这里出现错误的为黄色标记)
MsgBox "没有这个用户,请重新输入用户名!", vbOKOnly + vbExclamation, "警告"
txtUserName.SetFocus
Else
If Trim(mrc.Fields(1)) = Trim(txtPassword.Text) Then
OK = True
mrc.Close
Me.Hide
UserName = Trim(txtUserName.Text)
Else
MsgBox "输入密码不正确,请重新输入!", vbOKOnly + vbExclamation, "警告"
txtPassword.SetFocus
txtPassword.Text = ""
End If
End If
End If
miCount = miCount + 1
If miCount = 3 Then
Me.Hide
End If
Exit Sub
End Sub