inheritf.pas

图书管理系统：包括借书、还书、查询、添加、统计等功能。

unit inheritF;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, ImgList, ComCtrls, ToolWin, StdCtrls, Buttons, ExtCtrls, DB,
  ADODB, Grids, DBGrids;

type
  Tinherit = class(TForm)
    Panel1: TPanel;
    Label1: TLabel;
    Label2: TLabel;
    Label3: TLabel;
    Label4: TLabel;
    Label5: TLabel;
    Edit1: TEdit;
    Edit2: TEdit;
    Edit3: TEdit;
    BitBtn1: TBitBtn;
    ToolBar1: TToolBar;
    ToolButton1: TToolButton;
    ToolButton2: TToolButton;
    ToolButton3: TToolButton;
    ToolButton4: TToolButton;
    ToolButton6: TToolButton;
    ToolButton7: TToolButton;
    ToolButton8: TToolButton;
    ToolButton9: TToolButton;
    ToolButton10: TToolButton;
    ToolButton11: TToolButton;
    ImageList1: TImageList;
    DBGrid1: TDBGrid;
    Panel2: TPanel;
    ADOTable1: TADOTable;
    DataSource1: TDataSource;
    ADOQuery1: TADOQuery;
    procedure DataSource1DataChange(Sender: TObject; Field: TField);
    procedure ToolButton1Click(Sender: TObject);
    procedure ToolButton2Click(Sender: TObject);
    procedure ToolButton3Click(Sender: TObject);
    procedure ToolButton4Click(Sender: TObject);
    procedure ToolButton6Click(Sender: TObject);
    procedure ToolButton7Click(Sender: TObject);
    procedure ToolButton8Click(Sender: TObject);
    procedure ToolButton9Click(Sender: TObject);
    procedure ToolButton10Click(Sender: TObject);
    procedure ToolButton11Click(Sender: TObject);
    procedure FormClose(Sender: TObject; var Action: TCloseAction);
    procedure BitBtn1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
    //val为1表示新增删除等按钮等按钮处于enable状态，保存取消按钮处于
    //非enable状态，val为0表示情况相反.
    procedure SetButton(val:integer);
  end;

var
  inherit: Tinherit;

implementation

{$R *.dfm}
uses dataconnect;
  
//显示数据表中当前数据的数量
procedure Tinherit.DataSource1DataChange(Sender: TObject; Field: TField);
begin
  //显示数据数量

  label2.Caption:=inttostr(adotable1.RecordCount);
end;


//跳到第一条记录
procedure Tinherit.ToolButton1Click(Sender: TObject);
begin
 datasource1.DataSet.First;
end;
//跳到上一条记录
procedure Tinherit.ToolButton2Click(Sender: TObject);
begin
 datasource1.DataSet.Prior;
end;
//跳到下一条记录
procedure Tinherit.ToolButton3Click(Sender: TObject);
begin
 datasource1.DataSet.Next;
end;
//跳到最后一条记录
procedure Tinherit.ToolButton4Click(Sender: TObject);
begin
 datasource1.DataSet.Last;
end;
//新增记录
procedure Tinherit.ToolButton6Click(Sender: TObject);
begin
 datasource1.DataSet.Append;
 SetButton(0);

end;
//修改当前记录

procedure Tinherit.ToolButton7Click(Sender: TObject);
begin
 datasource1.Edit;
 SetButton(0);
end;
//删除当前记录
procedure Tinherit.ToolButton8Click(Sender: TObject);
begin
 if application.MessageBox('是否删除记录？','确认',MB_OKCANCEL)=IDOK then
  datasource1.DataSet.Delete;
end;
//确定所作操作
procedure Tinherit.ToolButton9Click(Sender: TObject);
begin
 datasource1.DataSet.Post;
 SetButton(1);
end;
//取消当前操作
procedure Tinherit.ToolButton10Click(Sender: TObject);
begin
 datasource1.DataSet.Cancel;
 SetButton(1);
end;
//关闭窗体
procedure Tinherit.ToolButton11Click(Sender: TObject);
begin
 close;
end;
//设置按钮状态enable or false
procedure Tinherit.SetButton(val: integer);
begin
if val=0 then
 (*根据如果当前没有记录，将新增，修改，删除以及首记录，上记录，下记录，尾记录等按钮enable设置为false
 而将保存，取消两按钮enable属性设置为true*)
 begin
  toolbutton1.Enabled:=false;
  toolbutton2.Enabled:=false;
  toolbutton3.Enabled:=false;
  toolbutton4.Enabled:=false;
  toolbutton6.Enabled:=false;
  toolbutton7.Enabled:=false;
  toolbutton8.Enabled:=false;
  toolbutton10.Enabled:=true;
  toolbutton11.Enabled:=true;
  //打开数据库控件的enable属性 准备后面修改、添加、删除记录
  panel2.Enabled:=true;
 end
else
 //当前有记录，则将新增，修改，删除以及首记录，上记录，下记录，尾记录等按钮enable设置为true
 //而将保存，取消两按钮enable属性设置为false.
 begin
    toolbutton1.Enabled:=true;
    toolbutton2.Enabled:=true;
    toolbutton3.Enabled:=true;
    toolbutton4.Enabled:=true;
    toolbutton6.Enabled:=true;
    toolbutton7.Enabled:=true;
    toolbutton8.Enabled:=true;
    toolbutton10.Enabled:=false;
    toolbutton11.Enabled:=false;
    //关闭板上数据库控件的enable属性
    panel2.Enabled:=false;
  end;

end;
//设置关闭窗体时的动作
procedure Tinherit.FormClose(Sender: TObject; var Action: TCloseAction);
begin
action:=cafree;
end;

//根据窗口中查询条件的设置来查询
procedure Tinherit.BitBtn1Click(Sender: TObject);
var
//设置一个整数，其二进制的三位分别代表查询条件1到3
//当某一个查询条件可见，也就是要使用这个条件时，相应的位置为1，否则置0
//例如第1，2个条件要使用而第3个不使用时，该整数二进制的值为110，也就是6
condition:integer;
begin
ToolButton6.Enabled:=true;
//初始化该参数，设为7，二进制数为111
 condition:=7;
//如果第1个条件不可用，则将该位置0，方法是和整数3（二进制011）进行与操作
if label3.Visible=false then
 condition:=(condition)and(3);

 //如果第2个条件不可用，则将该位置0，方法是和整数5（二进制101）进行与操作
if label4.Visible=false then
 condition:=(condition)and(5);

 //如果第3个条件不可用，则将该位置0，方法是和整数6（二进制110）进行与操作
if label5.Visible=false then
 condition:=(condition)and(6);

if condition=7 then//三个查询条件都存在的情况
 begin
   adoquery1.Close;
   adoquery1.SQL.Clear;
   adoquery1.SQL.Add('select * from '+adotable1.TableName);
   adoquery1.SQL.Add(' where('+label3.Caption+' like ''%'+edit1.Text+'%'')');
   adoquery1.SQL.Add('and('+label4.Caption+' like ''%'+edit2.Text+'%'')');
   adoquery1.SQL.Add('and('+label5.Caption+' like ''%'+edit3.Text+'%'')');
   adoquery1.Open;
   //将查询得到的数据复制到数据表中
   adotable1.Clone(adoquery1,ltUnspecified);

 end;

if condition=6 then//只存在两个查询条件的情况
 begin
   adoquery1.Close;
   adoquery1.SQL.Clear;
   adoquery1.SQL.Add('select * from '+adotable1.TableName);
   adoquery1.SQL.Add(' where('+label3.Caption+' like ''%'+edit1.Text+'%'')');
   adoquery1.SQL.Add('and('+label4.Caption+' like ''%'+edit2.Text+'%'')');
   adoquery1.Open;
   //将查询得到的数据复制到数据表中
   adotable1.Clone(adoquery1,ltUnspecified);

 end;

if condition=4 then //只存在一个查询条件的情况
 begin
   adoquery1.Close;
   adoquery1.SQL.Clear;
   adoquery1.SQL.Add('select * from '+adotable1.TableName);
   adoquery1.SQL.Add(' where('+label3.Caption+' like ''%'+edit1.Text+'%'')');
   adoquery1.Open;
   //将查询得到的数据通过复制到数据库中
   adotable1.Clone(adoquery1,ltUnspecified);
 end;


end;

end.