Looking at the Details for an Invoicing Application in Delphi

The new invoice form presents the user with a input form. You select a client from the dropdown box and then enter the amount for which you are invoicing. The total amount including the VAT will automatically be calculated and added to the total amount field of the form. Below is a listing of the code that makes all this happen:

unit newinv;

interface

uses

  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,

  Dialogs, Grids, DBGrids, DB, StdCtrls, Buttons, RpDefine, RpCon, RpConDS,

  RpRave, DBCtrls,math, ADODB;

type

  TForm2 = class(TForm)

    StaticText4: TStaticText;

    StaticText6: TStaticText;

    edAmount: TEdit;

    btnInsert: TBitBtn;

    BitBtn2: TBitBtn;

    edTotal: TEdit;

    StaticText7: TStaticText;

    GroupBox1: TGroupBox;

    StaticText1: TStaticText;

    StaticText3: TStaticText;

    qclients: TADOQuery;

    cb1: TComboBox;

    Memo1: TMemo;

    procedure BitBtn2Click(Sender: TObject);

    procedure btnInsertClick(Sender: TObject);

    procedure edAmountChange(Sender: TObject);

    procedure edTotalClick(Sender: TObject);

    procedure FormCreate(Sender: TObject);

    procedure FormShow(Sender: TObject);

    procedure Memo1Click(Sender: TObject);

  private

    { Private declarations }

  public

    { Public declarations }

  end;

var

  Form2: TForm2;

  tot:real;

implementation

 uses invmain;

{$R *.dfm}

procedure TForm2.BitBtn2Click(Sender: TObject);

begin

edit1.clear;

edit2.Clear;

edit3.clear;

edit4.Clear;

edit6.Clear;

close;

end;

procedure TForm2.btnInsertClick(Sender: TObject);

var

dt,d:tdatetime;

begin

dt:=now;

shortDateFormat := 'dd-mm-yyyy';

//if not (edamount.Text = '') and not (edtotal.Text='') and not (memo1.Text ='') then begin

if form1.ado1.active then form1.ado1.active:=false;

form1.ado1.TableName:='invoices';

form1.ado1.active:=true;

with form1.ado1 do

begin

Screen.Cursor := crHourGlass;

Insert;

FieldByName('invname').Text:= cb1.Text;

FieldByName('invdate').AsDateTime:=date;

FieldByName('status').text:='pending';

FieldByName('amount').AsCurrency:=strtofloat(edAmount.Text);

FieldByName('total').AsCurrency:=strtofloat(edTotal.Text);

FieldByName('notes').AsString:=memo1.Lines.Text;

post;

//form1.ado1.Active:=false;

// form1.ado1.Active:=true;

Screen.Cursor := crDefault;

  {end

  else

  begin

  messagedlg('Please fill in ALL the fields.',mtwarning,[mbOk], 0);

  end; }

end;

end;

procedure TForm2.edAmountChange(Sender: TObject);

begin

tot:= strtofloat(edAmount.Text);

end;

procedure TForm2.edTotalClick(Sender: TObject);

var

am:real;

begin

edtotal.Clear;

if tot > 0 then

begin

am:= (form1.vat / 100) * tot;

tot:=tot + am;

tot:=RoundTo(tot,-2);

edTotal.Text:=floattostr(tot);

end;

end;

procedure TForm2.FormCreate(Sender: TObject);

begin

qclients.ConnectionString:=form1.con;

qclients.Close;

qclients.SQL.Text:='Select name from clients';

qclients.Open;

while not qclients.EOF do

begin

  cb1.Items.Add(qclients.FieldByName('name').AsString);

  qclients.Next;

end;

end;

procedure TForm2.FormShow(Sender: TObject);

begin

tot:=0.0;

memo1.SelStart := 0;

    memo1.Perform(EM_SCROLLCARET, 0, 0);

  memo1.SetFocus;

end;

procedure TForm2.Memo1Click(Sender: TObject);

begin

memo1.SelStart := 0;

    memo1.Perform(EM_SCROLLCARET, 0, 0);

  memo1.SetFocus;

end;

end.

Once you click on the "Create New Invoice" button, the invoice information is inserted into the invoices table. The following code does that job:

dt:=now;

shortDateFormat := 'dd-mm-yyyy';

//if not (edamount.Text = '') and not (edtotal.Text='') and not (memo1.Text ='') then begin

if form1.ado1.active then form1.ado1.active:=false;

form1.ado1.TableName:='invoices';

form1.ado1.active:=true;

with form1.ado1 do

begin

Screen.Cursor := crHourGlass;

Insert;

FieldByName('invname').Text:= cb1.Text;

FieldByName('invdate').AsDateTime:=date;

FieldByName('status').text:='pending';

FieldByName('amount').AsCurrency:=strtofloat(edAmount.Text);

FieldByName('total').AsCurrency:=strtofloat(edTotal.Text);

FieldByName('notes').AsString:=memo1.Lines.Text;

post;

//form1.ado1.Active:=false;

// form1.ado1.Active:=true;

Screen.Cursor := crDefault;

The code itself is pretty straightforward. It opens up the table and calls the insert procedure. Then it simply inserts the newly-created values in the column fields of the invoice table and posts them to the database.