Delphi Community Edition database tutorials, part 2
Setting up the ClientDataset

UfoData, an application for UFO buffs

Let's build a small program for saving data of UFO sightings into a table. We have built the program using the "Delphi Community" edition. Even when you're not interested in UFOs, the techniques used will inspire you for other database applications.

Features:

• Add / modify / delete records
• Each record has a unique ID, containing the date plus case number for that date
• Upon adding or modifying, the ID is validated for contents and uniqueness
• The database is sorted on field ID
• Memo field for a short summary of each case
• Easily find a record containing a keyword (or part thereof) in "description" or "location"
• Surf to the webpage of the case in question

Here's how the application will look like when it's finished:

Preparations

1. If you haven't done so already, create a new folder \DelphiLand.
2. If you haven't done so already, create directory UfoData "under" \DelphiLand.
3. Next, download ufodata.zip and unzip it to this directory.

Setting up the project

1. Open Delphi and start a new project: menu File > New > VCL Forms Application
2. Drop a TPanel component on the form. Clear its property Caption and set property Align to alTop.
3. Drop the following components on the panel:
   
   ClientDataSet (Tool Palette, category Data Access)
   DataSource (Tool Palette, category Data Access)
   DBNavigator (Tool Palette, category Data Controls)
4. Below the panel drop a DBGrid (Tool Palette, category Data Controls)
5. Let's customize some of the properties of the components. In the Object Inspector, change these properties:
   
   

   Component	Property	New value
   Form	Caption	UfoData
   ClientDataSet	Name	cdsUfo
   DataSource	DataSet	cdsUfo
   	Name	dsUfo
   DBGrid	Align	alClient
   	DataSource	dsUfo
   DBNavigator	DataSource	dsUfo

6. Save your project, e.g. in folder \UfoData

Setting up the fields of the ClientDataSet

1. Add an OnCreate event handler to Form1: in the Object Inspector, go to the Events tab of Form1 and double click next to OnCreate.
2. In the code editor, complete the event handler as follows:
   

   procedure TForm1.FormCreate(Sender: TObject);
   begin
       cdsUfo.FieldDefs.Add('ID',       ftString, 10, False);
       cdsUfo.FieldDefs.Add('DESC',     ftString, 25, False);
       cdsUfo.FieldDefs.Add('LOCATION', ftString, 16, False);
       cdsUfo.FieldDefs.Add('COUNTRY',  ftString, 16, False);
       cdsUfo.FieldDefs.Add('CE',       ftString,  1, False);
       cdsUfo.FieldDefs.Add('SOURCE',   ftString, 25, False);
       cdsUfo.FieldDefs.Add('DURAT',    ftString, 16, False);
       cdsUfo.FieldDefs.Add('WIT',      ftString,  5, False);
       cdsUfo.FieldDefs.Add('SHAPE',    ftString, 10, False);
       cdsUfo.FieldDefs.Add('APPEAR',   ftString, 10, False);
       cdsUfo.FieldDefs.Add('SIZE',     ftString, 10, False);
       cdsUfo.FieldDefs.Add('OCC',      ftString,  3, False);
       cdsUfo.FieldDefs.Add('LINK2',    ftString, 50, False);
       cdsUfo.FieldDefs.Add('NOTES',    ftMemo,   10, False);
       cdsUfo.CreateDataSet;
   end;

   You can add and remove fields as desired, but don't remove the fields ID, DESC, LOCATION and LINK2 because these will be used later on in the project.
3. Run the project (press key F9).

Don't forget to save your project!

Note that you can add/edit/delete records in the grid. However, the contents of the database cdsUfo is not saved in a file when you stop the program. That's for our next tutorial.

Deploying on another computer

program Project1;

uses
  Vcl.Forms, 
  Unit1 in 'Unit1.pas' {Form1},
  [other units...,] 
  MIDASLIB;

Database Tutorials - Part 1     Database Tutorials - Part 3