How to use dbf tables: an example
lazarus / 16-Databases

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ecitoyen · 2013-12-26 00:21

Lazarus-Free Pascal & dbf Tables

As I am an user of LFP & dbf Tables, and cause i dont get enough
money for donation... i am offering some lines of source about
how i use dbf tables by using some procedure...

Look after:

1- be sure to get dbf in the <uses> section

Code: [Select]uses
  Classes, SysUtils, dbf, FileUtil, LResources, Forms, Controls,
Graphics,
  Dialogs, ExtCtrls, StdCtrls;

type

  { TForm1 }

  TForm1 = class(TForm)
...
...
    Dbf2: TDbf;
    Dbf3: TDbf;
    Dbf4: TDbf;

Code: [Select]
implementation

{ TForm1 }

Procedure usedbf2(Var pathdbf: string; Var namedbf: string; Var qtdbf:
integer; Var Dbf2: Tdbf);
begin
    Dbf2.FilePathFull := pathdbf;
    Dbf2.TableLevel := 7;
    Dbf2.Tablename := namedbf;
    Dbf2.Exclusive := True;
    Dbf2.Open;
    qtdbf:=Dbf2.recordcount;
end;
Procedure usedbf3(Var pathdbf: string; Var namedbf: string; Var qtdbf:
integer; Var Dbf3: Tdbf);
begin
    Dbf3.FilePathFull := pathdbf;
    Dbf3.TableLevel := 7;
    Dbf3.Tablename := namedbf;
    Dbf3.Exclusive := True;
    Dbf3.Open;
    qtdbf:=Dbf3.recordcount;
end;
Procedure usedbf4(Var pathdbf: string; Var namedbf: string; Var qtdbf:
integer; Var Dbf4: Tdbf);
begin
    Dbf4.FilePathFull := pathdbf;
    Dbf4.TableLevel := 7;
    Dbf4.Tablename := namedbf;
    Dbf4.Exclusive := True;
    Dbf4.Open;
    qtdbf:=Dbf4.recordcount;
end;
...
...
...
Procedure closedbf2(Var styledbf: integer; Var Dbf2: Tdbf);
begin
   if styledbf=2 then
    Dbf2.Post;
   Dbf2.Close;
   if styledbf=1 then
    Dbf2.Free;
end;

Procedure closedbf3(Var styledbf: integer; Var Dbf3: Tdbf);
begin
   if styledbf=2 then
    Dbf3.Post;
   Dbf3.Close;
   if styledbf=1 then
    Dbf3.Free;
end;

Procedure closedbf4(Var styledbf: integer; Var Dbf4: Tdbf);
begin
   if styledbf=2 then
    Dbf4.Post;
   Dbf4.Close;
   if styledbf=1 then
    Dbf4.Free;
end;

...
...

Procedure skipdbf2(Var fichedbf: integer; Var Dbf2: Tdbf);
begin
 if fichedbf=1 then
  Dbf2.First
 else
  Dbf2.Next;
end;
Procedure skipdbf3(Var fichedbf: integer; Var Dbf3: Tdbf);
begin
 if fichedbf=1 then
  Dbf3.First
 else
  Dbf3.Next;
end;
Procedure skipdbf4(Var fichedbf: integer; Var Dbf4: Tdbf);
begin
 if fichedbf=1 then
  Dbf4.First
 else
  Dbf4.Next;
end;

and now... after all procedure to access dbf tables are defined
we can use all of them in our others procedure...

an example

Code: [Select]procedure TForm1.FormCreate(Sender: TObject);
var

style: string;
repons: string;
pathdbf: string;
namedbf: string;
qtdbf: integer;
styledbf: integer;
fichedbf: integer;
nodbf: integer;
----comments
pathdbf is the path of the table
namedbf is the name of the table
qtdbf is a variable to get the recordcount of the table
-----
// Opening the Table

  pathdbf:=PATHTABLE;
  namedbf:=NAMETABLE;
  usedbf4(pathdbf,namedbf,qtdbf,Dbf4);
// Reading all records
//
  QTMES:=qtdbf;
  SetLength(MYARRAY,QTMES);
  i :=0;
  for l1:=1 to QTMES do
   begin
    fichedbf:=l1;
    skipdbf4(fichedbf,Dbf4);
    MES[i] := Trim(dbf4.FieldByName('TEXTE').AsString);
    i := i + 1;
   end;
//
//close the Table
  styledbf:=1;
  closedbf4(styledbf,Dbf4);
//
styledbf is the way we want to close the table
styledbf=0 is just to close
styledbf=1 is for posting before to close
styledbf=2 is for freeing memory after to close

The way we close the table is important, especially if you
want reuse many times the same procedure(as validate a name of
employee
in a table...)

Have fun... from Santa Clauss Groenland

And for anyone want to know more:
 Documentation

For official TDbf documentation PDF go to the SourceForge site. It may
be useful to keep that pdf alongside this document while reading.
http://sourceforge.net/projects/tdbf/files/TDbf documentation/TDbf
documentation 1.1/

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BigChimp · 2013-12-26 08:10

Thanks.

Code: [Select]writeln('Did you know about the code button? That would
make the spaghetti you posted above more readable.');
If there are things you miss on the tdbf tutorial at
http://wiki.lazarus.freepascal.org/Lazarus_Tdbf_Tutorial
please feel free to update it.

Thanks a lot,
BigChimp