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  • vb教程之在vb中实现分页处理数据库

  • 2017-09-19 21:58 来源:未知
作者:王勋 

当数据量太大时,最好的办法是分页处理数据库中的数据  
'PROVIDER=Microsoft.Jet.OLEDB.3.51;Data Source=E:\wang_xun\work\program\code\my_code\PrjPagination\bank.mdb; 
Private pTotal As Integer 
Private pCurrent As Integer 
Private pCon As ADODB.Connection 
Private pSize As Integer 
Private Sub cmdFirst_Click() 
pCurrent = 1 
Call InitListViewData 
Call InitDisplay 
End Sub 

Private Sub cmdGo_Click() 
pCurrent = CInt(txtVal) 
Call InitListViewData 
Call InitDisplay 
End Sub 

Private Sub cmdLast_Click() 
pCurrent = pTotal 
Call InitListViewData 
Call InitDisplay 
End Sub 

Private Sub cmdNext_Click() 
pCurrent = pCurrent + 1 
Call InitListViewData 
Call InitDisplay 
End Sub 

Private Sub cmdPrevious_Click() 
pCurrent = pCurrent - 1 
Call InitListViewData 
Call InitDisplay 
End Sub 

Private Sub Form_Load() 
pSize = 50 
Call AddHeader 
Call MakeCon 
Call InitListViewData 
Call InitDisplay 
End Sub 

Private Sub Form_QueryUnload(Cancel As Integer, UnloadMode As Integer) 
Cancel = 0 
End Sub 

Private Sub Form_Unload(Cancel As Integer) 
Call ClearVar 
End Sub 

Sub ClearVar() 
pTotal = 0 
pCurrent = 0 
Set pCon = Nothing 
End Sub 
Sub InitDisplay() 
If pCurrent > pTotal Then 
Call cmdFirst_Click 
End If 
Select Case pTotal 
Case Is > 0 
Call InitGoButton 
Select Case pCurrent 
Case 1 
cmdFirst.Enabled = False 
cmdLast.Enabled = True 
cmdPrevious.Enabled = False 
cmdNext.Enabled = True 
Case Is < pTotal And pCurrent > 1 
cmdFirst.Enabled = True 
cmdLast.Enabled = True 
cmdPrevious.Enabled = True 
cmdNext.Enabled = True 
Case Is = pTotal 
cmdFirst.Enabled = True 
cmdLast.Enabled = False 
cmdPrevious.Enabled = True 
cmdNext.Enabled = False 
Case Else 
cmdFirst.Enabled = False 
cmdLast.Enabled = False 
cmdPrevious.Enabled = False 
cmdNext.Enabled = False 
End Select 
Case Else 
cmdFirst.Enabled = False 
cmdLast.Enabled = False 
cmdPrevious.Enabled = False 
cmdNext.Enabled = False 
cmdGo.Enabled = False 
End Select 
labPage.Caption = "共" & Str(pTotal) & "页,当前是第" & Str(pCurrent) & "页" 
End Sub 

Private Sub txtnum_Change() 
pSize = CInt(txtnum.Text) 
End Sub 

Private Sub txtnum_ValidationError(InvalidText As String, StartPosition As Integer) 
pSize = 1 
End Sub 

'Private Sub txtNum_Change() 
'If Not (KeyAscii > 47 And KeyAscii < 58) Then 
' Beep 
' KeyAscii = 0 
'End If 
'End Sub 

Private Sub txtVal_Change() 
Call InitGoButton 
End Sub 

Private Sub txtVal_KeyPress(KeyAscii As Integer) 
If Not (KeyAscii > 47 And KeyAscii < 58) Then 
Beep 
KeyAscii = 0 
End If 
End Sub 
Sub InitGoButton() 
If Len(txtVal) > 0 Then 
If CInt(txtVal) > 0 And CInt(txtVal) <= pTotal Then 
cmdGo.Enabled = True 
Else 
cmdGo.Enabled = False 
End If 
Else 
cmdGo.Enabled = False 
End If 
End Sub 
Sub AddHeader() 
With lv 
.View = lvwReport 
.ColumnHeaders.Clear 
.ColumnHeaders.Add , , "ID", 800 
.ColumnHeaders.Add , , "名称", 2000 
End With 
End Sub 
Sub MakeCon() 
Dim a As New ADODB.Connection 
'a.Open "PROVIDER=Microsoft.Jet.OLEDB.3.51;Data Source=E:\wang_xun\work\program\code\my_code\PrjPagination\bank.mdb;" 
a.Open "PROVIDER=Microsoft.Jet.OLEDB.3.51;Data Source=" & App.Path & "\bank.mdb;" 
If Not a Is Nothing Then 
Set pCon = a 
End If 
Set a = Nothing 
End Sub 
Sub InitListViewData() 
Dim rs As ADODB.Recordset 
Dim s$, lp%, intSize%, sKey$ 
Dim m As ListItem 
lv.ListItems.Clear 
intSize = pSize 
s = "select * from sort" 
Set rs = New ADODB.Recordset 
rs.CursorLocation = adUseClient 
'Set rs = pCon.Execute(s) 
rs.Open s, pCon, , , adCmdText 
rs.PageSize = intSize 
pTotal = rs.PageCount 
If pTotal = 0 Then '空 
pCurrent = 0 
Else 
If pCurrent = 0 Then pCurrent = 1 
rs.AbsolutePage = pCurrent 
For lp = 1 To rs.PageSize 
If rs.EOF Then Exit For 
sKey = CStr(rs(0)) 
Set m = lv.ListItems.Add(, , sKey) 
If Not IsNull(rs(1)) Then m.SubItems(1) = Trim(rs(1)) 
rs.MoveNext 
Next 
End If 
Set rs = Nothing 
End Sub
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