help on fblib: lazarus + firebird
lazarus / 16-Databases

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AkiFoblesia · 2006-11-26 01:20

hi! i know how to create, query and update database using firebird,
however i'm new on database connections using lazarus.

i want to try using lazarus + firebird (embedded) via fblib.

can someone please write what i should write in the code explorer and
what i should enter in the object inspector in order to connect to an
existing database?

an example would definitely help - i tried the documentation but there
is not enough for the totally new to lazarus.

thanks  :wink:

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bmt · 2006-12-01 15:55

Last week i 've done some tests about databases & lazarus in Windows.
I didn't write any code in the code explorer but only using properties
in the object inspector of Lazarus.
I have installed Lazarus 0.9.18_win32 + MySQL 5.0.27 + FireBird 2.0 +
FBLib 0.85
----------------
method 1A: FireBird/InterBase (*.fdb) + Lazarus

IBConnection1 -> SQLTransaction1 -> SQLQuery1 -> DataSource1 ->
DBGrid1

Result: It works very good inside IDE (Run F9). Scrolling in DBGrid1
is OK  
------------
method 1B: FireBird/InterBase (*.fdb) + Lazarus

FBLDatabase1 -> FBLTransaction1 -> FBLDataset1 -> DataSource1 ->
DBGrid1

Result: Sometimes it works in IDE, if not then build it (Ctrl+F9) and
run it outside IDE  :?: . Scrolling gives problem when use key arrow-
up.  
---------------
method 2: mySQL database + Lazarus

MySQL50Connection1 -> SQLTransaction1 -> SQLQuery1 -> DataSource1 ->
DBGrid1

Result: It only works outside IDE  :?: . Scrolling in DBGrid1 is OK  
==============

Now more details in Object inspector:

---1A---
IBConnection1: (Properties)
DatabaseName: .....\employee.fdb,   Dialect:3,  HostName: localhost,
 KeepConnection: True,  Password: masterkey,  User: sysdba, Connected:
True,  (+Transaction: SQLTransaction1)

SQLTransaction1: (Properties)
+Database: IBConnection1,  Active: True

SQLQuery1: (Properties)
+Database: IBConnection1,  ParseSQL: True,  (ReadOnly: True),  SQL:
[...] select * from customer,  StatementType: stSelect,  +Transaction:
SQLTransaction1,  Active: True

Datasource1: (Properties)
+Dataset: SQLQuery1

DBGrid1: (Properties)
+DataSource: Datasource1

---1B---
FBLDatabase1: (Properties)
DBFile: .....\employee.fdb,   Host: localhost,  Password: masterkey,
 SQLDialect: 3,  User: sysdba, Connected: True

FBLTransaction1: (Properties)
+Database: FBLDatabase1

FBLDataset1: (Properties)
+Transaction: FBLTransaction1,  AutoStartTransaction: True,  Active:
True

Datasource1: (Properties)
+Dataset: FDLDataset1

DBGrid1: (Properties)
+DataSource: Datasource1

---2---
MySQL50Connection1: (Properties)
DBFile: .....\testSQLDB,   HostName: localhost,  KeepConnection: True,
LoginPrompt: True/False, Password: root,  User: root, Connected: True,
 (+Transaction: SQLTransaction1)

SQLTransaction1: (Properties)
+Database: MySQL50Connection1,  Active: True

SQLQuery1: (Properties)
+Database: MySQL50Connection1,  ParseSQL: True,  (ReadOnly: True),
 SQL: [...] select * from any_table,  StatementType: stSelect,
 +Transaction: SQLTransaction1,  Active: True

Datasource1: (Properties)
+Dataset: SQLQuery1

DBGrid1: (Properties)
+DataSource: Datasource1
========================

(PS. In Delphi, in order to use DBGrid we must use DatasetProvider &
ClientDataset before DataSource. But in Lazarus we don't need them.
Why ?)

Best regards

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jesusr · 2006-12-02 06:34

Are you using fblib 0.85?, I just went to their web site and they have
marked clearly that FBLDataset is Readonly, Unidirectional. This means
that you will have limited browsing capabilities, it can only browse
forward in the grid.

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Saverio · 2006-12-04 00:14

Well by default the FBLDataset is ReadOnly and Unidirectional but if
you declare:

FBLDataset.SQL.Text:= 'Select * from employee order by First_Name';
FBLDataset.Open;
FBLDataset.IsUniDirectional:= False;

you can browse any way.[/b]

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jesusr · 2006-12-04 00:56

It's nice to know that fblib is not only unidirectional, if it's so,
bmt could try to test turning off this property and try again, if
problem persist, bmt please submit a bug report using bug tracker, and
include as much details a you can (a test project to would be great).

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bmt · 2006-12-04 11:25

Thank you Saverio & Jesusr. It works now in IDE, scrolling is no more
trouble! Nice!
==========
unit Unit1;

{$mode objfpc}{$H+}

interface

uses
  Classes, SysUtils, LResources, Forms, Controls, Graphics, Dialogs,
  FBLDatabase, FBLTransaction, FBLDsql, DB, DBGrids, FBLDataset;

type

  { TForm1 }

  TForm1 = class(TForm)
    Datasource1: TDatasource;
    DBGrid1: TDBGrid;
    FBLDatabase1: TFBLDatabase;
    FBLDataset1: TFBLDataset;
    FBLTransaction1: TFBLTransaction;
    procedure FormCreate(Sender: TObject);
  private
    { private declarations }
  public
    { public declarations }
  end;

var
  Form1: TForm1;

implementation

{ TForm1 }

procedure TForm1.FormCreate(Sender: TObject);
begin
  FBLDataset1.IsUniDirectional:= False;
end;

initialization
  {$I unit1.lrs}

end.
==========
(I still use Lazarus 0.9.18 because of the working scrollbars for
Form)

I think the methods of IBConnenction & MySQLConnection are also nice
if they also work in IDE !