delphi简单的分页实现（高手可以不看）

适合初学者，练习几个控件的使用

1、先放一张界面控件布局：

4个button，2个label，1个edit，1个TRzsplitter（把界面分割成上下2部分），1一个adoquery，1个adoconnection，1个datdasource，1个DBgridEh（原生的dbgrid也可以）

2、双击窗体，编写连接数据库的代码：

 procedure TForm3.FormCreate(Sender: TObject);
 begin
   ADOConnection1.ConnectionString := 'Provider=SQLOLEDB.1;Persist Security Info=False;User ID=数据库用户名;Initial Catalog=数据库名字;PassWord=数据库密码;Data Source=数据库服务器IP';
   ADOConnection1.Connected := True;
   adoquery1.Connection := adoconnection1;
   adoquery1.SQL.clear;
   adoquery1.SQL.add('select top ' + Edit1.Text + ' * from TableName order by id');
   adoquery1.Open;
   datasource1.dataset := adoquery1;
   dbgrid1.DataSource := datasource1;
 end;

注意：adoconnection控件的LoginPrompt的属性值改为False（为什么是False自己可以去试一下）

3、双击 首页 按钮，编写代码：

 //第一页
 procedure TForm3.btnFirstPageClick(Sender: TObject);
 begin
   adoquery1.SQL.clear;
   adoquery1.SQL.add('select top ' + Edit1.Text + ' * from TableName order by id');
   adoquery1.Open;
   num2 := ;
 end;

4、双击 上一页 按钮，编写代码：

//上一页
procedure TForm3.btnPreviousPageClick(Sender: TObject);
begin
  dec(num2, StrToInt(Edit1.Text));
  if num2 >= StrToInt(Edit1.Text) then
  begin
    adoquery1.SQL.clear;
    adoquery1.SQL.Add('select top ' + Edit1.Text + ' * from TableName where id not in(select top ' + inttostr(num2) + ' id from TableName order by id) order by id');
    adoquery1.open;
  end
  else
  begin
    inc(num2, StrToInt(Edit1.Text));
    adoquery1.sql.clear;
    adoquery1.SQL.Add('select top ' + Edit1.Text + ' * from TableName order by id');
    adoquery1.Open;
  end;
end;

5、编写下一页 按钮 编写代码：

//下一页
procedure TForm3.btnNextPageClick(Sender: TObject);
begin
  adoquery1.SQL.clear;
  adoquery1.sql.add('select count(*) as countnum from TableName');
  adoquery1.Open;
  inc(num2, StrToInt(Edit1.Text));
  if num2 >= adoquery1.FieldByName('countnum').AsInteger then
  begin
    num2 := trunc(adoquery1.FieldByName('countnum').AsInteger / StrToInt(Edit1.Text)) * StrToInt(Edit1.Text);
  end;
  adoquery1.SQL.clear;
  adoquery1.SQL.Add('select top ' + Edit1.Text + ' * from TableName where id not in(select top ' + inttostr(num2) + ' id from TableName order by id) order by id');
  adoquery1.Open;
  if DBGrid1.DataSource.DataSet.RecordCount <=  then
  begin
    adoquery1.SQL.clear;
    adoquery1.SQL.Add('select top ' + Edit1.Text + ' * from TableName where id not in(select top ' + inttostr(num2-StrToInt(Edit1.Text)) + ' id from TableName order by id) order by id');
    adoquery1.Open;
  end;
end;

6、双击 最后一页 按钮，编写代码：

//最后一页
procedure TForm3.btnLastPageClick(Sender: TObject);
var
  val1 :Integer;
  val2 :Integer;
begin
  adoquery1.sql.clear;
  adoquery1.SQL.Add('select count(*) as countnum from TableName');
  adoquery1.Open;
  val1 := (adoquery1.FieldByName('countnum').AsInteger) mod  StrToInt(Edit1.Text);
  val2 := (adoquery1.FieldByName('countnum').AsInteger) - StrToInt(Edit1.Text);
  adoquery1.SQL.Clear;
  num2 := val2;
  if val1 = 0then
  begin
    adoquery1.SQL.Add('select top ' + Edit1.Text + ' * from TableName where id not in(select top ' + IntToStr(val2) + ' id from TableName order by id) order by id');
  end
  else
  begin
    adoquery1.SQL.Add('select top ' + IntToStr(val1) + ' * from TableName where id not in(select top ' + IntToStr(val2) + ' id from TableName order by id) order by id');
  end;
  adoquery1.Open;
end;

7、完整代码：

 unit Unit3;

 interface

 uses
   Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
   Dialogs, DB, ADODB, StdCtrls, Grids, DBGrids, RzDBGrid, ExtCtrls, RzPanel, RzSplit, DBGridEhGrouping, GridsEh,
   DBGridEh;

 type
   TForm3 = class(TForm)
     btnFirstPage: TButton;
     btnNextPage: TButton;
     btnPreviousPage: TButton;
     btnLastPage: TButton;
     ADOQuery1: TADOQuery;
     ADOConnection1: TADOConnection;
     DataSource1: TDataSource;
     Edit1: TEdit;
     lblCount1: TLabel;
     lblCount2: TLabel;
     RzSplitter1: TRzSplitter;
     DBGrid1: TDBGridEh;
     procedure btnFirstPageClick(Sender: TObject);
     procedure FormCreate(Sender: TObject);
     procedure btnNextPageClick(Sender: TObject);
     procedure btnPreviousPageClick(Sender: TObject);
     procedure btnLastPageClick(Sender: TObject);
   private
     { Private declarations }
   public
     { Public declarations }
   end;

 var
   Form3: TForm3;
   num2: integer;

 implementation

 {$R *.dfm}

 //第一页
 procedure TForm3.btnFirstPageClick(Sender: TObject);
 begin
   adoquery1.SQL.clear;
   adoquery1.SQL.add('select top ' + Edit1.Text + ' * from TableName order by id');
   adoquery1.Open;
   num2 := ;
 end;

 //最后一页
 procedure TForm3.btnLastPageClick(Sender: TObject);
 var
   val1 :Integer;
   val2 :Integer;
 begin
   adoquery1.sql.clear;
   adoquery1.SQL.Add('select count(*) as countnum from TableName');
   adoquery1.Open;
   val1 := (adoquery1.FieldByName('countnum').AsInteger) mod  StrToInt(Edit1.Text);
   val2 := (adoquery1.FieldByName('countnum').AsInteger) - StrToInt(Edit1.Text);
   adoquery1.SQL.Clear;
   num2 := val2;
   if val1 = 0then
   begin
     adoquery1.SQL.Add('select top ' + Edit1.Text + ' * from TableName where id not in(select top ' + IntToStr(val2) + ' id from TableName order by id) order by id');
   end
   else
   begin
     adoquery1.SQL.Add('select top ' + IntToStr(val1) + ' * from TableName where id not in(select top ' + IntToStr(val2) + ' id from TableName order by id) order by id');
   end;
   adoquery1.Open;
 end;

 //下一页
 procedure TForm3.btnNextPageClick(Sender: TObject);
 begin
   adoquery1.SQL.clear;
   adoquery1.sql.add('select count(*) as countnum from TableName');
   adoquery1.Open;
   inc(num2, StrToInt(Edit1.Text));
   if num2 >= adoquery1.FieldByName('countnum').AsInteger then
   begin
     num2 := trunc(adoquery1.FieldByName('countnum').AsInteger / StrToInt(Edit1.Text)) * StrToInt(Edit1.Text);
   end;
   adoquery1.SQL.clear;
   adoquery1.SQL.Add('select top ' + Edit1.Text + ' * from TableName where id not in(select top ' + inttostr(num2) + ' id from TableName order by id) order by id');
   adoquery1.Open;
   if DBGrid1.DataSource.DataSet.RecordCount <=  then
   begin
     adoquery1.SQL.clear;
     adoquery1.SQL.Add('select top ' + Edit1.Text + ' * from TableName where id not in(select top ' + inttostr(num2-StrToInt(Edit1.Text)) + ' id from TableName order by id) order by id');
     adoquery1.Open;
   end;
 end;

 //上一页
 procedure TForm3.btnPreviousPageClick(Sender: TObject);
 begin
   dec(num2, StrToInt(Edit1.Text));
   if num2 >= StrToInt(Edit1.Text) then
   begin
     adoquery1.SQL.clear;
     adoquery1.SQL.Add('select top ' + Edit1.Text + ' * from TableName where id not in(select top ' + inttostr(num2) + ' id from TableName order by id) order by id');
     adoquery1.open;
   end
   else
   begin
     inc(num2, StrToInt(Edit1.Text));
     adoquery1.sql.clear;
     adoquery1.SQL.Add('select top ' + Edit1.Text + ' * from TableName order by id');
     adoquery1.Open;
   end;
 end;

 procedure TForm3.FormCreate(Sender: TObject);
 begin
   ADOConnection1.ConnectionString := 'Provider=SQLOLEDB.1;Persist Security Info=False;User ID=数据库用户名;Initial Catalog=数据库名字;PassWord=数据库密码;Data Source=数据库服务器IP';
   ADOConnection1.Connected := True;
   adoquery1.Connection := adoconnection1;
   adoquery1.SQL.clear;
   adoquery1.SQL.add('select top ' + Edit1.Text + ' * from TableName order by id');
   adoquery1.Open;
   datasource1.dataset := adoquery1;
   dbgrid1.DataSource := datasource1;
 end;

 end.