Question

I’ve been tasked with patching a Delphi software to work with a new database(mssql) structure.
In the previous database(mssql), all the columns being read were in the same table.
In the new version the file_name and class_name are in a different table as the quantity values.
I believe I can fix this by writing a Join for these two database tables.
Issue is, I’m not familiar with Delphi!
The current code is below.
How do I get these two databases to join into one?

dataTable=style001
dataTable1=style

THANKS!!!

  dataTable.Active := True;
  datatable.Open;
  dataTable1.Active := True;
  datatable1.Open;

  while not datatable1.Eof do
  begin
    Application.ProcessMessages;

    file_name := trim(datatable1.FieldByName('code').asString) + '.jpg';
    class_name := trim(datatable1.FieldByName('category').asString);

    if not FileExists(picfolder + file_name) then
    begin
      dataTable1.next;
      continue;
    end;

    instock := datatable.FieldByName('onhand').asString;
    TryStrToInt(instock, instock_num);

    quantity := datatable.FieldByName('onorder').asString;
    TryStrToInt(quantity, num);

    num := instock_num - num;

    is_active := ( num > 10 );


    for i := 0 to file_count-1 do
    begin
      if is_active = active_class[file_class[i]] then
      if SameText(files[i],file_name) then
      begin // use TStringList instead
        if SameText(class_name, classes[file_class[i]]) then // same class
        begin
          file_ok[i] := true;
          class_ok[file_class[i]] := true;
        end;
        break;
      end;
    end;

    if class_name <> '' then class_name := class_name + '\';
    dest := picfolder + active_path[is_active] + class_name;
    deldest := picfolder + active_path[not is_active] + class_name;

    {$I-}

    if FileExists(deldest + file_name) then
      DeleteFile(PChar(deldest + file_name ));

    if not FileExists(dest + file_name) then
    begin
      ForceDirectories(dest);
      CopyFile(PChar(picfolder + file_name ), PChar(dest + file_name ), true );
    end;

    dataTable1.next;
  end;

  for i := 0 to file_count-1 do
    if not file_ok[i] then
    begin // delete wrong file if empty
//      ShowMessage('problem: ' + picfolder + active_path[active_class[file_class[i]]] + classes[file_class[i]] + '\' + files[i]);
      DeleteFile(picfolder + active_path[active_class[file_class[i]]] + classes[file_class[i]] + '\' + files[i]);
    end;
  for i := 0 to class_count-1 do
    if not class_ok[i] then
    begin // delete old class if empty
//      ShowMessage('problem: ' + picfolder + active_path[active_class[i]] + classes[i] + '\' );
      RemoveDir(picfolder + active_path[active_class[i]] + classes[i] + '\' );
    end;


  beep;
  dataTable.Active := False;
  dataTable1.Active := False;

Answer 1

The JOIN is inside the SQL request, not the consuming loop code you are showing here.

You have to use a TQuery instead of two TTable, and write a SQL select for joining the two tables.

You have to modify the SQL request, add the two tables in the FROM clause of the SELECT, and a JOINture in the WHERE clause. See this article about JOIN.