Delphi Community database tutorials, part 4
Improving the data entry

Sorting the records

In order to have the UFO sightings sorted by field "ID", select cdsUfo in the Design view.
In the Object Inspector, next to IndexFieldNames, type: ID

Data entry

Entering data directly in the DBGrid is not very safe, because the data is not verified before storing it. Let's improve on this.

Firstly, we don't want the user to change data directly in the grid:
in the Object Inspector, set property AutoEdit of dsUfo to False.

Next, we add a panel with a few data controls.

1. Drop a TPanel somewhere below the DBGrid.
   Set its property Align to alBottom.
2. Drop a DBMemo on this panel.
   In the Object Inspector, set its property DataSource to dsUfo and set property DataField to NOTES.
3. Below the DBMemo, drop another panel. Set its Name to panEdit and the property Visible to False.
4. Drop 13 TDBEdit components onto the panel panEdit.
   Set the property DataSource of all these edit-boxes to dsUfo.
   Set the other properties as follows:

   Component	Name	DataField
   TDBEdit1	edID	ID
   TDBEdit2	edDesc	DESC
   TDBEdit3	edLocation	LOCATION
   TDBEdit4	edCountry	COUNTRY
   TDBEdit5	edCE	CE
   TDBEdit6	edSource	SOURCE
   TDBEdit7	edDurat	DURAT
   TDBEdit8	edWit	WIT
   TDBEdit9	edShape	SHAPE
   TDBEdit10	edAppear	APPEAR
   TDBEdit11	edSize	SIZE
   TDBEdit12	edOcc	OCC
   TDBEdit13	edLink2	LINK2

5. Below the DBEdits, add two buttons. Name the first one btnSave and the other one btnCancel.
6. Add OnClick event handlers for the buttons:

   procedure TForm1.btnSaveClick(Sender: TObject);
   begin
     cdsUfo.Post;
   end;
   
   procedure TForm1.btnCancelClick(Sender: TObject);
   begin
     cdsUfo.Cancel;
   end;

Let's write some source code, using the ClientDataSet's events.

1. Firstly, we write a procedure that handles the enabling or disabling of certain components, depending from the fact if we are in the course of modifying a record, or just browsing the table. Without this procedure, we would have to repeat almost the same code in 4 places.
   In the interface section, under Private declarations, add the following line:

   procedure UpdateGUI(Modify: Boolean);

2. In the implementation section, add the following procedure:
   

   procedure TForm1.UpdateGUI(Modify: Boolean);
   begin
     DBGrid1.Enabled := not Modify;
     DBNavigator1.Enabled := not Modify;
     edSearch.Enabled := not Modify;
     btnSearch.Enabled := not Modify;
     btnWeb.Enabled := not Modify;
     panEdit.Visible := Modify;
     if Modify then
       edID.SetFocus
     else
       DBGrid1.SetFocus;
   end;
   

3. Select dsUfo. In the Object Inspector, tab Events, double click next to BeforeEdit.
   Complete the new event handler as follows:

   procedure TForm1.cdsUfoBeforeEdit(DataSet: TDataSet);
   begin
     UpdateGUI(True);
   end;

4. Likewise, create an event handler for BeforeInsert and complete the code:

   procedure TForm1.cdsUfoBeforeInsert(DataSet: TDataSet);
   begin
     UpdateGUI(True);
   end;

5. For the event AfterCancel:

   procedure TForm1.cdsUfoAfterCancel(DataSet: TDataSet);
   begin
     UpdateGUI(False);
   end;

6. For the event AfterPost:

   procedure TForm1.cdsUfoAfterPost(DataSet: TDataSet);
   begin
     DataChanged := True;
     UpdateGUI(False);
   end;

Database Tutorials - Part 3 Database Tutorials - Part 5