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    <p><strike>I'm assuming that the database access in a thread is of no problem for you.</strike></p> <p>For a complete example of a threaded access to a dbExpress database (including feedback to the main thread), see the examples made by <a href="https://stackoverflow.com/users/45145/marco-cantu">Marco Cantù</a> here: <a href="http://blog.marcocantu.com/blog/dbexpress_firebird_examples.html" rel="nofollow noreferrer">dbexpress_firebird_examples</a>.</p> <p>It involves putting all the database connection setup in a <code>TDataModule</code> and creating an instance of this datamodule for each threaded access.</p> <p>Anyway, to make the GUI informed about the background thread process with an animated Gif, here is an example:</p> <p><img src="https://i.stack.imgur.com/WynfG.jpg" alt="enter image description here"></p> <pre><code>unit TestAnimatedScreen; interface uses Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics, Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Vcl.Imaging.GIFImg, Vcl.ExtCtrls; type TMyEndNotify = procedure (value: Boolean) of object; type TMyThread = class(TThread) private fEndNotification : TMyEndNotify; procedure NotifyEndOfThread; protected procedure Execute; override; public Constructor Create(endNotification : TMyEndNotify); end; type TMainForm = class(TForm) Image1: TImage; Button1: TButton; procedure Button1Click(Sender: TObject); private { Private declarations } FShowAnimation : Boolean; procedure SetShowAnimation(value : Boolean); public { Public declarations } property ShowAnimation : Boolean read FShowAnimation write SetShowAnimation; end; var MainForm: TMainForm; implementation {$R *.dfm} procedure TMyThread.NotifyEndOfThread; begin if Assigned(fEndNotification) then fEndNotification(False); end; constructor TMyThread.Create(endNotification: TMyEndNotify); begin Inherited Create(false); fEndNotification := endNotification; Self.FreeOnTerminate := True; // Free automatically end; procedure TMyThread.Execute; begin try {Add your database access code here} Sleep(5000); // Simulate lengthy process finally Synchronize(NotifyEndOfThread); end; end; { TMainForm } procedure TMainForm.Button1Click(Sender: TObject); begin ShowAnimation := True; TMyThread.Create(Self.SetShowAnimation); end; procedure TMainForm.SetShowAnimation(value: Boolean); begin FShowAnimation := Value; if FShowAnimation then begin {Add animation code here} Button1.Enabled := false; Button1.Caption := 'Processing, please wait ...'; (Image1.Picture.Graphic as TGIFImage).AnimateLoop := glEnabled; (Image1.Picture.Graphic as TGIFImage).Animate := true; end else begin {Stop animation} (Image1.Picture.Graphic as TGIFImage).Animate := false; Button1.Caption := 'Start lengthy process'; Button1.Enabled := True; end; end; end. </code></pre> <hr> <pre><code>object MainForm: TMainForm Left = 0 Top = 0 Caption = 'MainForm' ClientHeight = 265 ClientWidth = 236 Color = clBtnFace Font.Charset = DEFAULT_CHARSET Font.Color = clWindowText Font.Height = -11 Font.Name = 'Tahoma' Font.Style = [] OldCreateOrder = False PixelsPerInch = 96 TextHeight = 13 object Image1: TImage Left = 8 Top = 8 Width = 200 Height = 200 AutoSize = True IncrementalDisplay = True end object Button1: TButton Left = 8 Top = 224 Width = 200 Height = 25 Caption = 'Start lengthy process' TabOrder = 0 OnClick = Button1Click end end </code></pre> <p>Should you have an older Delphi version than Delphi 2007, see <a href="https://stackoverflow.com/q/9573572/576719">How to use Animated Gif in a delphi form</a> for more information about how to implement an animated GIF.</p> <p>The animated GIF I used can be found <a href="http://en.wikipedia.org/wiki/Graphics_Interchange_Format" rel="nofollow noreferrer">here</a>.</p>
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    1. POHow to open ClientDataSet (master/detail) in separate thread(different of main thread)
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    1. COthanks LU RD, its perfect
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    2. CObut the database access in a thread is a problem for me. when im try to use i, have access violation
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    3. COOK, then I suggest you edit your question and add the code for database access plus a good description of the error.
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