Very Computer

Hi,

I've found how to create/delete indexes at run-time, but I've a
problem with the MDX file.

The file is automatically created (if not already there) when I create
the first index, and automatically removed when I remove the last
index. That's fine.

But if I remove (the end user will do that for sure) the MDX from disk
while there are still indexes than Delphi refuse to open the table.

Is there a why (with VCL, no calls to BDE please) to say: ok, forget
about any indexes and files and start again from scratch ?

        Thanks, Luca.

Bart G

I've always found this to be the biggest drawback to the MDX format,. If
this is a big headache for you, you might consider using a different
index format. Successware has Apollo which I've heard good things
about... I've also heard that D3 has native support for FoxPro
indexes...

Quote:> Is there a why (with VCL, no calls to BDE please) to say: ok, forget
> about any indexes and files and start again from scratch ?

--
Roland Bouchereau

--
Roland Bouchereau

Here's how to programmatically clear the "has production index" flag
from your .DBF header.

Use caution - this routine will alter any file you pass it as long as it
has a .dbf extension - you will have to confirm that it is really a
dbase table prior to calling this.

--
Damon Pugh
Vision Software
http://www.vsnsoft.com

procedure DropProductionIndex(Name:String);  
{Name parameter is filename without extension}
var
  f: file of byte;
  b: byte;
  position:integer;
  mdxName:String;

begin

  {I+}  {Handle I/O errors as Exceptions}

  try
    {The 28th byte of a dBase V header controls whether
    the table has a production index or not.  We can use
    low-level file i/o to set this byte to 0.  This byte
    gets set back to 1 when an index gets created, so we
    don't have to worry about reactivating the production
    index.}

    b:=0;

    assignFile(f,Name+'.dbf');
    FileMode:=of_Write+of_Share_Exclusive;
    reset(f);
    seek(f, 28);
    write(f, b);
    closefile(f);

    {Now, delete the .MDX file}
    {$IFDEF Win32}
    if FileExists(Name+'.mdx') then DeleteFile(PChar(Name+'.mdx'));
    {$ELSE}
    if FileExists(Name+'.mdx') then DeleteFile(Name+'.mdx');
    {$ENDIF}

  except
    raise EDataBaseError.Create(
    'Could not delete index '+name+'.mdx.  File may be in use.  Make
sure all users are out of system and retry'
    );
  end;
end;