C++Builder - Database tutorial, part 2

In this part of our tutorial, we shall visualize the database by adding a "browser".

Start by downloading the source code Articles2.zip and next unzip it to folder \CppProjects\Articles2.

Database Browser

Open project Articles2 in C++Builder and have a look at the form in Design mode. Note the TStringGrid component, named Grid, that is used for browsing the database.

We set up the stringgrid at the start of the application, as can be seen here:

void __fastcall TForm1::FormCreate(TObject *Sender)
{
  // ... lines with old existing code
  // ...
  
  // New code:
  Grid->ColWidths[0] = 60;
  Grid->ColWidths[1] = 120;
  Grid->ColWidths[2] = 80;
  Grid->ColWidths[3] = 60;
  Grid->Cells[0][0] = "ID";
  Grid->Cells[1][0] = "Name";
  Grid->Cells[2][0] = "Price";
  Grid->Cells[3][0] = "Stock";
}

Each time a record is changed, this must be reflected in the TStringGrid. For this purpose, we added a private method to the form, UpdateGrid() (see Unit1.h).
Here's the code for this function (see Unit1.cpp):

void TForm1::UpdateGrid()
{
  int index;
  Grid->RowCount = Articles->Count + 1;
  for (index = 0; index < Articles->Count; index++)
  {
    TArticle *Art = static_cast<TArticle*>(Articles->Objects[index]);
    Grid->Cells[0][index + 1] = Articles->Strings[index];
    Grid->Cells[1][index + 1] = Art->Name;
    Grid->Cells[2][index + 1] = FormatFloat("0.00", Art->Price);
    Grid->Cells[3][index + 1] = IntToStr(Art->Stock);
  }
}

User friendly

We made the application somewhat more user friendly. Therefore, we start off by hiding Panel1 and only show it when needed:

• In FormCreate(), we added a statement that initially hides Panel1.
• In btnAdd(), we added a statement that shows Panel1.
• Both in btnOKClick() and in btnCancelClick(), we again hide Panel1.

Improved searching

Our routine for finding an article by its ID is changed: instead of showing Panel1, it now highlights the line of the article in the stringgrid:

void __fastcall TForm1::btnFindIDClick(TObject *Sender)
{
  int index;
  if (Articles->Find(edFind->Text, index)) {
    stStatus->Caption = " Article was found ";
    Grid->Row = index + 1;
    Grid->SetFocus();
  }
  else
    stStatus->Caption = " Article " + edFind->Text + " not found ";
}

Finally, we added a button for finding an article by its Name.
We walk through all the records one by one, until we find a suitable one. Don't worry, this is very fast, even for thousands of records!

void __fastcall TForm1::btnFindNameClick(TObject *Sender)
{
  int index, posit;
  int foundwhere = -1;
  String S = edFind->Text;
  S = S.UpperCase(); // Find case-insensitive
  for (index = 0; index < Articles->Count; index++)
  {
    TArticle *Art = static_cast<TArticle*>(Articles->Objects[index]);
    Name = Art->Name;
    Name = Name.UpperCase(); // Find case-insensitive
    posit = Name.Pos(S);
    if (posit > 0) {
      foundwhere = index;
      break; // if found, break out of the loop
    }
  }
  if (foundwhere > -1) {
    stStatus->Caption = " Article was found ";
    Grid->Row = foundwhere + 1;
    Grid->SetFocus();
  }
  else
    stStatus->Caption = " Article " + edFind->Text + " not found ";
}