unit2.~pas

简单的图书馆查询系统

unit Unit2;

interface

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

type
  TForm2 = class(TForm)
    Label1: TLabel;
    Edit1: TEdit;
    Label2: TLabel;
    Edit2: TEdit;
    Button1: TButton;
    Label3: TLabel;
    DBGrid1: TDBGrid;
    Button2: TButton;
    DataSource1: TDataSource;
    Table1: TTable;
    Table2: TTable;
    Table3: TTable;
    Query1: TQuery;
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form2: TForm2;

implementation

{$R *.dfm}

procedure TForm2.Button1Click(Sender: TObject);
var
  loc1:boolean;
  loc2:boolean;

  loc4: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;
      
loc1:=table1.Locate('学号',edit1.Text,locOp);
loc2:=table2.Locate('书号',edit2.Text,locOp);

loc4:=table3.locate('学号;书号',vararrayof([edit1.text,edit2.text]),locOp);
if loc1=false then
  begin
    showmessage('无此学号，请重新输入');
    abort;
  end;
if loc2=false then
  begin
    showmessage('无此书号，请重新输入');
    abort;
  end;

if loc4=true then
  begin
    showmessage('您已借阅过此书');
    abort;
  end;
if Table2.FieldByName('余书').value=0 then
  begin
    showmessage('sorry,此书已全部借出');
    abort;
  end;
table3.InsertRecord([edit1.text,edit2.text,date,date+14]);
Table2.Edit;
Table2.FieldByName('余书').value:=Table2.FieldByName('余书').value-1;
Table2.Post;
query1.Close;
query1.SQL.Clear;
query1.SQL.Add('select 学号,书号,书名,借阅日期,归还日期 from lent,book  where book.书号=lent.书号 and 学号 like ''%'+trim(Edit1.text)+'%''');
query1.Open;

showmessage('您已成功借阅');
edit1.Clear;
edit2.Clear;

end;
procedure TForm2.Button2Click(Sender: TObject);
begin
  close;
end;

end.