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：

 1 procedure TForm3.FormCreate(Sender: TObject);
 2 begin
 3   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';
 4   ADOConnection1.Connected := True;
 5   adoquery1.Connection := adoconnection1;
 6   adoquery1.SQL.clear;
 7   adoquery1.SQL.add('select top ' + Edit1.Text + ' * from TableName order by id');
 8   adoquery1.Open;
 9   datasource1.dataset := adoquery1;
10   dbgrid1.DataSource := datasource1;
11 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：

1 //第一页
2 procedure TForm3.btnFirstPageClick(Sender: TObject);
3 begin
4   adoquery1.SQL.clear;
5   adoquery1.SQL.add('select top ' + Edit1.Text + ' * from TableName order by id');
6   adoquery1.Open;
7   num2 := 0;
8 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 <= 0 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：

  1 unit Unit3;
  2 
  3 interface
  4 
  5 uses
  6   Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  7   Dialogs, DB, ADODB, StdCtrls, Grids, DBGrids, RzDBGrid, ExtCtrls, RzPanel, RzSplit, DBGridEhGrouping, GridsEh,
  8   DBGridEh;
  9 
 10 type
 11   TForm3 = class(TForm)
 12     btnFirstPage: TButton;
 13     btnNextPage: TButton;
 14     btnPreviousPage: TButton;
 15     btnLastPage: TButton;
 16     ADOQuery1: TADOQuery;
 17     ADOConnection1: TADOConnection;
 18     DataSource1: TDataSource;
 19     Edit1: TEdit;
 20     lblCount1: TLabel;
 21     lblCount2: TLabel;
 22     RzSplitter1: TRzSplitter;
 23     DBGrid1: TDBGridEh;
 24     procedure btnFirstPageClick(Sender: TObject);
 25     procedure FormCreate(Sender: TObject);
 26     procedure btnNextPageClick(Sender: TObject);
 27     procedure btnPreviousPageClick(Sender: TObject);
 28     procedure btnLastPageClick(Sender: TObject);
 29   private
 30     { Private declarations }
 31   public
 32     { Public declarations }
 33   end;
 34 
 35 var
 36   Form3: TForm3;
 37   num2: integer;
 38 
 39 implementation
 40 
 41 {$R *.dfm}
 42 
 43 //第一页
 44 procedure TForm3.btnFirstPageClick(Sender: TObject);
 45 begin
 46   adoquery1.SQL.clear;
 47   adoquery1.SQL.add('select top ' + Edit1.Text + ' * from TableName order by id');
 48   adoquery1.Open;
 49   num2 := 0;
 50 end;
 51 
 52 //最后一页
 53 procedure TForm3.btnLastPageClick(Sender: TObject);
 54 var
 55   val1 :Integer;
 56   val2 :Integer;
 57 begin
 58   adoquery1.sql.clear;
 59   adoquery1.SQL.Add('select count(*) as countnum from TableName');
 60   adoquery1.Open;
 61   val1 := (adoquery1.FieldByName('countnum').AsInteger) mod  StrToInt(Edit1.Text);
 62   val2 := (adoquery1.FieldByName('countnum').AsInteger) - StrToInt(Edit1.Text);
 63   adoquery1.SQL.Clear;
 64   num2 := val2;
 65   if val1 = 0then
 66   begin
 67     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');
 68   end
 69   else
 70   begin
 71     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');
 72   end;
 73   adoquery1.Open;
 74 end;
 75 
 76 //下一页
 77 procedure TForm3.btnNextPageClick(Sender: TObject);
 78 begin
 79   adoquery1.SQL.clear;
 80   adoquery1.sql.add('select count(*) as countnum from TableName');
 81   adoquery1.Open;
 82   inc(num2, StrToInt(Edit1.Text));
 83   if num2 >= adoquery1.FieldByName('countnum').AsInteger then
 84   begin
 85     num2 := trunc(adoquery1.FieldByName('countnum').AsInteger / StrToInt(Edit1.Text)) * StrToInt(Edit1.Text);
 86   end;
 87   adoquery1.SQL.clear;
 88   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');
 89   adoquery1.Open;
 90   if DBGrid1.DataSource.DataSet.RecordCount <= 0 then
 91   begin
 92     adoquery1.SQL.clear;
 93     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');
 94     adoquery1.Open;
 95   end;
 96 end;
 97 
 98 //上一页
 99 procedure TForm3.btnPreviousPageClick(Sender: TObject);
100 begin
101   dec(num2, StrToInt(Edit1.Text));
102   if num2 >= StrToInt(Edit1.Text) then
103   begin
104     adoquery1.SQL.clear;
105     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');
106     adoquery1.open;
107   end
108   else
109   begin
110     inc(num2, StrToInt(Edit1.Text));
111     adoquery1.sql.clear;
112     adoquery1.SQL.Add('select top ' + Edit1.Text + ' * from TableName order by id');
113     adoquery1.Open;
114   end;
115 end;
116 
117 procedure TForm3.FormCreate(Sender: TObject);
118 begin
119   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';
120   ADOConnection1.Connected := True;
121   adoquery1.Connection := adoconnection1;
122   adoquery1.SQL.clear;
123   adoquery1.SQL.add('select top ' + Edit1.Text + ' * from TableName order by id');
124   adoquery1.Open;
125   datasource1.dataset := adoquery1;
126   dbgrid1.DataSource := datasource1;
127 end;
128 
129 end.

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