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Truncate all BLOBs in the specified field to zero. If any error occurs while removing BLOB information, stop at that record.

This example uses the following input:

 fDbiTruncateBlob(BiotestTbl, BiotestTbl.FieldByName('Notes').Index);

 

The procedure is:

procedure fDbiTruncateBlob(BlobTbl: TTable; Index: Word);

var

 hCur: hDBICur;

 pRecBuf: pBYTE;

begin

 hCur := nil;

 // Make sure the field specified is a BLOb type

if (BlobTbl.Fields[Index] is TblobField) then begin

   pRecBuf := AllocMem(BlobTbl.RecordSize);

  try

     // Clone a cursor to the table so data aware controls keep their place

     Check(DbiCloneCursor(BlobTbl.Handle, False, False, hCur));

     Check(DbiSetToBegin(hCur));

     // Iterate throuth the table removing BLOb information

    while (DbiGetNextRecord(hCur, dbiWRITELOCK, pRecBuf, nil) = DBIERR_NONE)

    do begin

       // BDE funcstions use a 1 for the first field vs. Delphi's 0;

       // add 1 to the index

       Check(DbiOpenBlob(hCur, pRecBuf, Index + 1, dbiREADWRITE));

       Check(DbiTruncateBlob(hCur, pRecBuf, Index + 1, 0));

       Check(DbiModifyRecord(hCur, pRecBuf, True));

       Check(DbiFreeBlob(hCur, pRecBuf, Index + 1));

    end;

  finally  // Close cloned cursor and free record buffer memory

    if (hCur <> nil) then

       Check(DbiCloseCursor(hCur));

     FreeMem(pRecBuf, BlobTbl.RecordSize);

  end;

end

else

  raise EDatabaseError.Create('Field: ' +

     BlobTbl.Fields[Index].FieldName + ', is not a blob type');

end;