Oracle ODBC BLOB examples.

Question

We are currently writing a VB application to harvest data from an Access 2000 database, which is to large to convert to 97 and use migration workbench, and stuff it into an Oracle 8 database, which already has the table structures from the Access dataabase created in it. We are running into a problem in transfering OLE objects in Access to BLOBs in Oracle. Can anyone give some insight / code examples?
Thanks,
Matt Shoultz

Answer 1

When you get a chance, can you post the ADO version, or a link to it?
thanks.
Chris
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Justin Cave ([email protected]):
Unfortunately, I've never dealt with OLE objects in Access. I'm more than happy to help with BLOB's, though.
I'm posting a document below that covers reading & writing BLOB's with RDO under VB. Unfortunately, it's a little long, so I hope it doesn't get mangled too badly. If there's interest in an ADO version, let me know that as well and I'll post it on another thread.
If folks would like me to e-mail them a copy of this document, drop me a line. Expect it to take me at least a few days to reply to these requests, though.
PURPOSE
The code below should demonstrate how to read from and write to Oracle
8 BLOB datatypes.
SCOPE & APPLICATION
Experienced Visual Basic Developers.
RELATED DOCUMENTS
None.
The code below this demonstrates how to create a Visual Basic project
to read from and write to BLOB datatypes. It was written and tested using Visual
Basic 5 and RDO 2. The Oracle 8.0.5.2 ODBC driver was also used and an
Oracle 8.0.5 database.
Disclaimer:
This sample is provided for educational purposes only. It is NOT supported by
Oracle World Wide Technical Support. The sample has been tested and appears to
work as intended. However, you should always test in YOUR environment before
relying on it.
'Form Image Description
'~~~~~~~~~~~~~~~~~~~~~~
'The form needs 1 OLE control (OLE1) and 1 small text box (text 1) default value '1'
'it also needs 4 command buttons (AddNew,LoadFrom,LoadFromFile,SaveToDB)
'ODBC Datasource
'~~~~~~~~~~~~~~~
'Configure an 8.0.5.2 Oracle ODBC Driver Datasource named 'V805'
'Code required to generate database objects.
'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
'drop table tblTestBlob;
'CREATE TABLE tblTestBlob
' DATA_ID NUMBER(5,0),
' DATA_BlobData BLOB,
' DATA_MemoData CLOB
'INSERT INTO TBLTESTBLOB VALUES (1,EMPTY_BLOB(), EMPTY_CLOB());
Option Explicit
Dim en As rdoEnvironment
Dim Qd As rdoQuery
Dim Cn As rdoConnection
Dim Rs As rdoResultset
Dim SQL As String
Dim DataFile As Integer, Fl As Long, Chunks As Integer
Dim Fragment As Integer, Chunk() As Byte, I As Integer
Const ChunkSize As Integer = 16384
Dim fileName As String
Private Sub PipeToFile(sFileName)
Dim iFile As Integer
iFile = FreeFile
Open sFileName For Binary As iFile
Me.OLE1.SaveToFile iFile
DoEvents
Close iFile
End Sub
Private Sub AddNew_Click()
Dim sSQL As String
sSQL = "Select * from TBLTESTBLOB"
On Error GoTo errorhandler
Set Rs = Cn.OpenResultset(sSQL, rdOpenKeyset, rdConcurValues)
If Rs Is Nothing Or Rs.Updatable = False Then
MsgBox "Cant open or write to result set"
Exit Sub
End If
Rs.AddNew
Rs("DATA_ID") = Val(Me.Text1)
Rs("DATA_BLOBDATA").AppendChunk Null
Rs("DATA_MEMODATA").AppendChunk Null
Rs.Update
Rs.Close
Set Rs = Nothing
Exit Sub
errorhandler:
MsgBox "Add new click"
MsgBox Err.Number
MsgBox Err.Description
End Sub
Private Sub Form_Load()
On Error GoTo errorhandler
Set Cn = New rdoConnection
Cn.CursorDriver = rdUseOdbc
Cn.Connect = ";dsn=" & "V805" & ";uid=" & "scott" & ";pwd=" & "tiger"
Cn.EstablishConnection
Exit Sub
errorhandler:
MsgBox "Form Load"
MsgBox Err.Number
MsgBox Err.Description
End Sub
Private Function GetBLOBLength() As Long
Dim sSQL As String
Dim oResult As RDO.rdoResultset
On Error GoTo errorhandler
sSQL = "SELECT DBMS_LOB.GETLENGTH(DATA_BLOBDATA) FROM TBLTESTBLOB WHERE DATA_ID=" & Text1
Set oResult = Cn.OpenResultset(sSQL, rdOpenStatic)
GetBLOBLength = Val("" & oResult.rdoColumns(0).Value)
oResult.Close
Set oResult = Nothing
Exit Function
errorhandler:
MsgBox "Get BLOB Length"
MsgBox Err.Number
MsgBox Err.Description
End Function
Private Sub LoadFrom_Click()
Dim iNumBlocks As Integer
Dim lColSize As Long
Dim lBlockSize As Long
Dim byteData() As Byte
Dim lOffSet As Long
Dim iDestFileNum As Integer
Dim lLeftOver As Long
Dim iCount As Integer
Dim sSQL As String
On Error GoTo errorhandler
sSQL = "Select * from TBLTESTBLOB WHERE DATA_ID=" & Val(Text1)
Set Rs = Cn.OpenResultset(sSQL, rdOpenKeyset, rdConcurValues)
If Rs Is Nothing Or Rs.Updatable = False Then
MsgBox "Cant open or write to result set"
Exit Sub
End If
If Not Rs.EOF Then
lColSize = GetBLOBLength()
If lColSize <> 0 Then
iDestFileNum = FreeFile
Open "c:\TEST.DAT" For Binary As iDestFileNum
lBlockSize = 10000
iNumBlocks = lColSize \ lBlockSize
lLeftOver = lColSize Mod lBlockSize
For iCount = 1 To iNumBlocks
ReDim byteData(lBlockSize)
byteData() = Rs("DATA_BLOBDATA").GetChunk(lBlockSize) 'note offset not used by RDO (?)
Put iDestFileNum, , byteData()
lOffSet = lOffSet + lBlockSize 'note offset not used by RDO (?)
Next iCount
ReDim byteData(lLeftOver)
byteData() = Rs("DATA_BLOBDATA").GetChunk(lLeftOver) 'note offset not used by RDO (?)
Put iDestFileNum, , byteData()
Close iDestFileNum
iDestFileNum = FreeFile
Open "c:\TEST.DAT" For Binary As iDestFileNum
Me.OLE1.ReadFromFile iDestFileNum
Close iDestFileNum
End If
End If
Rs.Close
Set Rs = Nothing
Exit Sub
errorhandler:
MsgBox "Load From click"
MsgBox Err.Number
MsgBox Err.Description
End Sub
Private Sub LoadFromFile_Click()
' Locates a file and sets the Filename to this file.
On Error GoTo errorhandler
With CommonDialog1
.Filter = "*.*"
.ShowOpen
fileName = .fileName
End With
FileName_Change
Exit Sub
errorhandler:
MsgBox "Load from file"
MsgBox Err.Number
MsgBox Err.Description
End Sub
Private Sub SaveToDB_Click()
Dim sSQL As String
Dim sTempName As String
On Error GoTo errorhandler
sTempName = "c:\TEST.DAT"
Kill sTempName
PipeToFile sTempName
sSQL = "Select DATA_ID, DATA_BLOBDATA from TBLTESTBLOB WHERE DATA_ID=" & Val(Text1)
'sSQL = "Select DATA_Field1, DATA_IMAGE from TBLBIGDATA WHERE DATA_FIELD1=" & Val(Text1)
Set Rs = Cn.OpenResultset(sSQL, rdOpenKeyset, rdConcurValues)
If Rs Is Nothing Or Rs.Updatable = False Then
MsgBox "Cant open or write to result set"
Exit Sub
End If
If Not Rs.EOF Then
Rs.Edit
End If
DataFile = 1
Open sTempName For Binary Access Read As DataFile
Fl = LOF(DataFile) ' Length of data in file
If Fl = 0 Then
Close DataFile
Exit Sub
End If
Chunks = Fl \ ChunkSize
Fragment = Fl Mod ChunkSize
Rs("DATA_BLOBDATA").AppendChunk Null
ReDim Chunk(Fragment)
Get DataFile, , Chunk()
Rs("DATA_BLOBDATA").AppendChunk Chunk()
ReDim Chunk(ChunkSize)
For I = 1 To Chunks
Get DataFile, , Chunk()
Rs("DATA_BLOBDATA").AppendChunk Chunk()
Next I
Close DataFile
Rs.Update
Rs.Close
Set Rs = Nothing
MsgBox "Finish"
Exit Sub
errorhandler:
MsgBox "Save to DB"
MsgBox Err.Number
MsgBox Err.Description
End Sub
Private Sub FileName_Change()
On Error GoTo errorhandler
Me.OLE1.CreateEmbed fileName
Exit Sub
errorhandler:
MsgBox "File Name Change"
MsgBox Err.Number
MsgBox Err.Description
End Sub
Justin Cave
ODBC Development<HR></BLOCKQUOTE>
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