help.. TBDF
lazarus / 16-Databases

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suddendeath · 2011-04-18 08:55

Ok, so i'm a idiot! i downloaded the TBDF PDF and i don't get howto
do search and retrieve information this is what i got so far can
anyone help show me

{ notes :
   Create( apath ) make sure that the path has delimiter \
}




unit Unit2;

{$mode objfpc}{$H+}

interface

uses
  Classes, SysUtils,
  Dbf, DB, Dbf_Common;  // fpc tbdf

const

  db_UserFile = 'USER.DBF';


type

  TUserDatabase = class
  private
    FDBFile: TDbf;
  public
    constructor Create(aPath: string);
    destructor Destroy; override;

    function PackDataBase: boolean;
    function NumUsers : LongInt;

    function UserExist(aString : AnsiString) : LongInt;
    function LoadUser(aString : AnsiString  Var aUser : TUserRec) :
boolean;
    function SaveUser(Var aUser : TUserRec) : boolean;
    function UpdateUser(Var aUser : TUserRec) : boolean;

  protected

  end;

implementation

{ lots of work here build the table bigger with entire user record }

constructor TUserDataBase.Create(aPath: string);
begin
  FDBFile := TDbf.Create(nil);
  FDBFile.FilePath := aPath;
  FDBFile.TableLevel := 7;
  FDBFile.TableName := db_UserFile;
  if not (SysUtils.FileExists(aPath + db_UserFile)) then
  begin
    FDBFile.Exclusive := True;
    with FDBFile.Fields do
    begin
      try
        Add('User_ID', ftAutoInc, 0, True);
        Add('Real_Name', ftString, 35, True);
        Add('User_Name', ftString, 35, True);
        Add('User_Password', ftString, 20, True);
        Add('User_SL', ftInteger, 0, True);
        Add('User_Flags', ftString, 52, True);
        Add('User_Email', ftString, 80, True);
        FDBFile.CreateTable;
        FDBFile.Open;
        FDBFile.AddIndex('idxUserID', 'User_ID', [ixPrimary,
ixUnuque]);
        FDBFile.AddIndex('idxUser_Name', 'User_Name',
[ixCaseInsensitive]);
        FDBFile.AddIndex('idxReal_Name', 'Real_Name',
[ixCaseInsensitive]);
        FDBFile.Exclusive := False;
      finally
      end;
    end;
  end
  else
    FDBFile.Open;
end;

destructor TUserDataBase.Destroy;
begin
 FDBFile.Exclusive:=True;
 FDBFile.PackTable;
 FDBFile.RegenerateIndexes;
 FDBFile.Close;
 FDBFile.Free;
end;

function TUserDataBase.PackDataBase: boolean;
begin
 FDBFile.Exclusive:=True;
 FDBFile.PackTable;
 FDBFile.RegenerateIndexes;
 FDBFile.Close;  // not sure if i have to close - open but better safe
 FDBFile.Open;
 FDBFile.Exclusive:=False;
end;

Function TUserDataBase.NumUsers : LongInt;
begin
 FDBFile.RecordCount;
end;

Function TUserDataBase.UserExist(aString : ansiString) : longint;
begin
  FDBFile.Filter:='User_ID'[aString];
  FDBFile.Filtered:=True;;
end;

end.

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javivf · 2011-04-27 08:23

Maybe with this...

Quote from: suddendeath on April 18, 2011, 10:55:24 amFunction
TUserDataBase.NumUsers : LongInt;
begin
  if not(FDBFile.Active) then
    FDBFile.Open;
  FDBFile.RecordCount;
end;

Function TUserDataBase.UserExist(aString : ansiString) : longint;
begin
  if not(FDBFile.Active) then
    FDBFile.Open;
  FDBFile.Filter:='User_ID'[aString];
  FDBFile.Filtered:=True;;
end;

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joseme · 2011-04-27 10:47

To be a function, your code must return something. My version of code:
Code: [Select]Function TUserDataBase.NumUsers : LongInt;
begin
  if not(FDBFile.Active) then
    FDBFile.Open;
  result := FDBFile.RecordCount;
end;

Function TUserDataBase.UserExist(aString : ansiString) : boolean;
begin
  if not(FDBFile.Active) then
    FDBFile.Open;
  FDBFile.Filter:='User_ID'[aString];
  FDBFile.Filtered:=True;
  result := not FDBFile.Eof;
end;            
not sure if you  can filter  a DBF without closing, setting filter and
condition and opening...

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garydale · 2011-07-25 18:45

The filter condition can be set and changed with an open database.
It's applied dynamically so it can be slow - especially with complex
filter conditions.

Personally, I find the use of the Boolean "Filtered" condition to be
annoying. If the filter is a null string, the table isn't filtered. If
it isn't a null string then it should be applied.

I don't see any advantage to making us turn a switch on and off when
one can just as easily set and unset the filter string.

Perhaps someone can explain why Filtered is used?

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garlar27 · 2011-07-25 19:08

QuoteI don't see any advantage to making us turn a switch on and off
when one can just as easily set and unset the filter string.

Perhaps someone can explain why Filtered is used?I think you should
ask that to Delphi's developpers. Because that's the way they allways
did it...

But for me it has sense, spetially if you have a filter which is built
progresively in your code. And if you want to disable that filter for
a moment then you have to build it again