unit4.pas

简单的图书馆查询系统

unit Unit4;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, DB, DBTables;

type
  TForm4 = class(TForm)
    Button1: TButton;
    Label1: TLabel;
    Label2: TLabel;
    Edit1: TEdit;
    Edit2: TEdit;
    Button2: TButton;
    Table1: TTable;
    Table2: TTable;
    Table3: TTable;
    Label3: TLabel;
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form4: TForm4;

implementation

{$R *.dfm}

procedure TForm4.Button1Click(Sender: TObject);
begin
  close;
end;

procedure TForm4.Button2Click(Sender: TObject);
var

  loc2:boolean;
  loc3:boolean;
  locOp:TlocateOptions;
begin
  locOp:=[loCaseInsensitive];
    if (edit1.text='') or (edit2.text='') then
      begin
        showmessage('请输入学号和书号!');
        abort;
      end;

  loc3:=table2.Locate('书号',edit2.Text,locOp);
  loc2:=table3.locate('学号;书号',vararrayof([edit1.Text,edit2.Text]),locop);
if loc2=false then
  begin
    showmessage('无此记录，请重新输入');
    abort;
  end;
Table2.Edit;
Table2.FieldByName('余书').value:=Table2.FieldByName('余书').value+1;
Table2.Post;
table3.Locate('学号;书号',VarArrayof([edit1.Text,edit2.Text]),locOp);
table3.delete;
showmessage('还书成功');
edit1.clear;
edit2.clear;

end;

end.