???? ??????? ???? ?? ???? SQL Server ??? ????? ADO ????? ?????? ????

???? ?????? ???? ??????
???? ID: 180368 - ?? ???????? ?? ?????? ??? ?? ?? ???? ???? ???? ??.
?? ???? ???????? ?? ???? ??? ??. ??? "???? ??" ???? ?? ?????????? ???? ??? ?? ?? ?? ??????? ???? ???? ?????.
??? ?? ??????? ???? | ??? ?? ??????? ????

?? ????? ??

??????

?? ???? ????????? ???? ?? ?? ?? ????? ?? ?? ??? ??? ?????? (??????? ??? ????????/BLOBS) ActiveX ???? ???????? (ADO) ?? ????? ???? ??? ?????? ???? ?? ??? ???? ????? ?? accomplished ?? ?? ????? ????GetChunk, ??AppendChunk??? ADODB RecordSet ????? ???????? ?? ????????

???? ???????

??? ?? ??? ????? ?????????

  1. ??? ??? ????????? ?????? Form1 ???????? ??? ?? ???? ??..
  2. ??????????????? ??,??????, ?? Microsoft ActiveX ???? ???????? ????????? ??? ?? ?????? ??? ?????
  3. ???? ????????? ?? ??? ??? ???? ??????? ?????, ?? ????? ??? ???????:
       Global cn As ADODB.Connection
       Global cmd1 As ADODB.Command
       Global rsset As ADODB.Recordset
    
       Const BLOCKSIZE As Long = 4096
    
       Public Sub ColumnToFile(Col As ADODB.Field, DiskFile As String)
        'Retrieves data from the database and puts it into a temp file on
        'the hard drive.
        'The size of the chunk is in the variable BLOCKSIZE (4096).
    
       Dim NumBlocks As Long  'Holds the number of chunks.
       Dim LeftOver As Long   '# of chars left over after last whole chunk.
       Dim strData As String
       Dim DestFileNum As Long
       Dim I As Long
       Dim ColSize As Long
    
       'Make sure that you aren't in an empty recordset.
        If Not rsset.EOF And Not rsset.BOF Then
        ColSize = Col.ActualSize
    
       'If filelength > 0, then it is soiled:
       ' throw away contents.
        If Len(Dir$(DiskFile)) > 0 Then
          Kill DiskFile
        End If
    
        DestFileNum = FreeFile
        Open DiskFile For Binary As DestFileNum
        NumBlocks = ColSize \ BLOCKSIZE
        LeftOver = ColSize Mod BLOCKSIZE
    
        'Now Write data to the file in chunks.
         For I = 1 To NumBlocks
         strData = String(BLOCKSIZE, 0)
         strData = Col.GetChunk(BLOCKSIZE)
         Put DestFileNum, , strData
         Next I
         strData = String(LeftOver, 0)
         strData = Col.GetChunk(LeftOver)
         Put DestFileNum, , strData
    
         Close DestFileNum
         End If
          End Sub
    
         Sub FileToColumn(Col As ADODB.Field, DiskFile As String)
         'Takes data from the temp file and saves it to the database.
    
           Dim strData As String
           Dim NumBlocks As Long
           Dim FileLength As Long
           Dim LeftOver As Long
           Dim SourceFile As Long
           Dim I As Long
    
           SourceFile = FreeFile
           Open DiskFile For Binary Access Read As SourceFile
           FileLength = LOF(SourceFile)
           If FileLength = 0 Then
            Close SourceFile
            MsgBox DiskFile & " Empty or Not Found."
           Else
            NumBlocks = FileLength \ BLOCKSIZE
            LeftOver = FileLength Mod BLOCKSIZE
            Col.AppendChunk Null
            strData = String(BLOCKSIZE, 0)
            For I = 1 To NumBlocks
             Get SourceFile, , strData
             Col.AppendChunk strData
            Next I
            strData = String(LeftOver, 0)
            Get SourceFile, , strData
            Col.AppendChunk strData
            rsset.Update
            Close SourceFile
           End If
          End Sub
    
          Public Sub FileToForm(DiskFile As String, SomeControl As Control)
           'Retrieves data from the temp file and puts it onto the control.
    
           Dim SourceFile As Long
           Dim FileLength As Long
           Dim strData As String
    
           SourceFile = FreeFile
           Open DiskFile For Binary Access Read As SourceFile
           FileLength = LOF(SourceFile)
           If FileLength = 0 Then
            Close SourceFile
            MsgBox DiskFile & " Empty or Not Found."
           Else
            strData = String(FileLength, 0)
            Get SourceFile, , strData
            SomeControl.Text = strData
            Close SourceFile
           End If
          End Sub
    
          Sub FormToFile(DiskFile As String, SomeControl As Control)
           'Saves data from the form into a temp file on the local hard drive.
    
           Dim DestinationFile As Long
           Dim FileLength As Long
           Dim strData As String
    
           If Len(Dir$(DiskFile)) > 0 Then
            Kill DiskFile
           End If
           DestinationFile = FreeFile
           Open DiskFile For Binary As DestinationFile
           strData = SomeControl.Text
           Put DestinationFile, , strData
           Close DestinationFile
          End Sub
  4. Form1 ???????? ?? ????? ????:
    1. ????? ???RichTextBox??? ????, ?? ???????? ???????"rtbText." ???? ?? ??? ???
    2. ????? ???CommandButton??? ????, ?? ???????? ???????property to "cmdPrev" and theCaptionproperty to "Prev."
    3. ????? ???CommandButton??? ????, ?? ???????? ???????property to "cmdNext" and theCaptionproperty to "Next."
    4. ????? ???CommandButton??? ????, ?? ???????? ???????property to "cmdSave" and itsCaptionproperty to "Update."
  5. Paste the following code into the form:
       Option Explicit
    
       Dim DiskFile As String
    
          Private Sub cmdNext_Click()
           If (rsset.RecordCount > 0) And (Not rsset.EOF) Then
            rsset.MoveNext
            If Not rsset.EOF Then
             rtbText.Text = ""
             ColumnToFile rsset.Fields("pr_info"), DiskFile
             FileToForm DiskFile, rtbText
            Else
             rsset.MoveLast
            End If
           End If
          End Sub
    
          Private Sub cmdPrev_Click()
           If (rsset.RecordCount > 0) And (Not rsset.BOF) Then
            rsset.MovePrevious
            If Not rsset.BOF Then
             rtbText.Text = ""
             ColumnToFile rsset.Fields("pr_info"), DiskFile
             FileToForm DiskFile, rtbText
            Else
             rsset.MoveFirst
            End If
           End If
          End Sub
    
          Private Sub cmdSave_Click()
           FormToFile DiskFile, rtbText
           FileToColumn rsset.Fields("pr_info"), DiskFile
          End Sub
    
          Private Sub Form_Activate()
           rtbText.Text = ""
           If rsset.RecordCount > 0 Then
            rsset.MoveFirst
            ColumnToFile rsset.Fields("pr_info"), DiskFile
            FileToForm DiskFile, rtbText
           End If
          End Sub
    
          Private Sub Form_Load()
    
           Dim ConnectString As String
           Dim anerror As ADODB.Error
           Dim Sql As String
    
           On Error GoTo handler
    
           DiskFile = App.Path & "\BLOB.txt"
    
           'Set the connect string to use pubs on your SQL server.
           ConnectString = _
           "Driver={SQL SERVER};Server=<yourserver>;Database=pubs;UID=sa;pwd=;"
           Sql = "SELECT pr_info FROM pub_info;"
           Set cn = New ADODB.Connection
           cn.ConnectionString = ConnectString
           cn.Open
           Set rsset = New ADODB.Recordset
           rsset.Open Sql, cn, adOpenKeyset, adLockOptimistic, adCmdText
          Exit Sub
    
          handler:
           For Each anerror In cn.Errors
            Debug.Print anerror.Number & ":  " & anerror.Description & _
            " - " & anerror.SQLState
           Next anerror
          End Sub
  6. Change the ServerName in the connectstring to your server name.
  7. Run the sample project. TheRichTextBoxwill contain the first record of the recordset.
  8. ????? ????,next. Notice that the contents of theRichTextBoxchange to the next record until you reach the last record. Thenextbutton calls the recordset'sMoveNextmethod and then calls theColumnToFile, ??FileToForm????????
  9. ????? ????,Prev. Notice that the contents of theRichTextBoxchange to the previous record until you reach the first record. ThePrevbutton calls the recordset'sMovePreviousmethod and then calls theColumnToFile, ??FileToForm????????
  10. Type something new in the text box, and then click??????to modify the text field in whatever record you are on. The??????button calls theFormToFile, ??FileToColumnmethods, which in turn calls the recordset's???????????? ??? The new data should get updated in the database.

???

???? ID: 180368 - ????? ???????: 22 ????? 2014 - ??????: 4.0
???? ???? ???? ??:
  • Microsoft ActiveX Data Objects 2.7
  • Microsoft Visual Basic 5.0 Professional Edition
  • Microsoft Visual Basic 6.0 Professional Edition
  • Microsoft Visual Basic 5.0 Enterprise Edition
  • Microsoft Office 97 Professional Edition
??????: 
kbnosurvey kbarchive kbdatabase kbhowto kbmt KB180368 KbMthi
???? ?????? ????????
??????????: ?? ???? ?? ???? ??????? ?? ????? ?? Microsoft ????-?????? ?????????? ?????? ?????? ???? ??? ??. Microsoft ???? ??? ????-???????? ?? ????-???????? ????? ?????? ?? ???? ???????? ???? ?? ???? ????? ????? ??? ?? ??? ?????? ?? ???? ???? ???? ??? ????? ??. ???????, ????-???????? ???? ????? ???? ???? ???? ???. ?????, ????????, ?????-???? ?? ??????? ?? ???????? ?? ???? ???, ???? ?? ??? ?????? ???? ???? ??? ????? ??? ?? ???? ??. Microsoft ??????? ??? ???? ?? ?????? ?? ??????????, ????????? ?? ??? ?????? ?? ???? ????? ?? ???? ???????? ?? ??? ???? ????? ?? ??? ????????? ???? ??. Microsoft ????-?????? ?????????? ?? ????? ?????? ?? ?? ??? ??.
?????????? ?? ??????? ????????? ??????? ??:180368

??????????? ???

 

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