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*.mdx lost problem (dBase 7)

Posted on 1998-11-06
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Last Modified: 2013-11-24
Hi,

If the *.mdx files lost, I used to set the byte number 28 to 0 in *.dbf file.
But Dbase 7 changed DBF file structure. How can I do with it?

Or I think using BDE API is better than to modify the file physically.

Thanks.
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Question by:yysun
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6 Comments
 
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Expert Comment

by:dwwang
ID: 1345988
Hi, yysun, I think you are the yysun on Rich Forum, right?

See http://www.inprise.com/devsupport/bde/bdeapiex, index secction of BDE functions.
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Author Comment

by:yysun
ID: 1345989
ÄúºÃ£¡dwwang,¾ÓÈ»µ½ÕâÀïÀ´·¢²ÆÁË£¿

I've alreadyed check that document, but all the functions there should use a valid handle of the table. But if the mdx file missed the table can not be opened. So no handle can be used?

What can I do then?
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Expert Comment

by:elkiors
ID: 1345990
Is it not possible to rebuild the index files from info within the table ?

Darren
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dwwang earned 200 total points
ID: 1345991
Use Database Desktop, open the table, when prompt error, select the "open and detach", then the index infomation will be removed from the table.
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Author Comment

by:yysun
ID: 1345992
How can I do it using Delphi like Database Desktop does?
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Expert Comment

by:elkiors
ID: 1345993
Have a look at TTable.DeleteIndex and TTable.IndexDef methods and properties.

you could also call the BDE directly. Below is a block of code that was given to me as an answer on E-E for compacting dBase and Paradox tables. There's a bit in it that uses the BDE to re-index and re-structure the tables. Maybe this is of some use.

unit DBPack;

interface

uses BDE, DBTables, DB, sysutils;

procedure PackTable(Table: TTable);

implementation

// This example will pack a Paradox or dBASE table therfore removing already deleted rows in a table.
// This function will also regenerate all out-of-date indexes (maintained indexes).
// This example uses the following input:
// PackTable(Table1)
// The function is defined as follows:

// Pack a Paradox or dBASE table
// The table must be opened execlusively before calling this function...
procedure PackTable(Table: TTable);
var
  Props: CURProps;
  hDb: hDBIDb;
  TableDesc: CRTblDesc;

begin
  // Make sure the table is open exclusively so we can get the db handle...
  if Table.Active = False then raise EDatabaseError.Create('Table must be opened to pack');
  if Table.Exclusive = False then raise EDatabaseError.Create('Table must be opened exclusively to pack');

  // Get the table properties to determine table type...
  Check(DbiGetCursorProps(Table.Handle, Props));

  // If the table is a Paradox table, you must call DbiDoRestructure...
  if Props.szTableType = szPARADOX then
  begin
    // Blank out the structure...
    FillChar(TableDesc, sizeof(TableDesc), 0);
    //  Get the database handle from the table's cursor handle...
    Check(DbiGetObjFromObj(hDBIObj(Table.Handle), objDATABASE, hDBIObj(hDb)));
    // Put the table name in the table descriptor...
    StrPCopy(TableDesc.szTblName, Table.TableName);
    // Put the table type in the table descriptor...
    StrPCopy(TableDesc.szTblType, Props.szTableType);
    // Set the Pack option in the table descriptor to TRUE...
    TableDesc.bPack := True;
    // Close the table so the restructure can complete...
    Table.Close;
    // Call DbiDoRestructure...
    Check(DbiDoRestructure(hDb, 1, @TableDesc, nil, nil, nil, FALSE));
  end
  else
    // If the table is a dBASE table, simply call DbiPackTable...
    if Props.szTableType = szDBASE then
      Check(DbiPackTable(Table.DBHandle, Table.Handle, nil, szDBASE, TRUE))
    else
      // Pack only works on PAradox or dBASE; nothing else...
      raise EDatabaseError.Create('Table must be either of Paradox or dBASE ' + 'type to pack');
        Table.Open;
end;

end.


Regards

Darren

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