unit1.pas

这有很多Delphi应用的例子

unit Unit1;

interface

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

type
  TForm1 = class(TForm)
    DataSource1: TDataSource;
    DBGrid1: TDBGrid;
    ButtonSelect: TButton;
    ButtonInsert: TButton;
    ButtonDelete: TButton;
    ButtonChange: TButton;
    Label1: TLabel;
    Edit1: TEdit;
    Query1: TQuery;
    procedure ButtonSelectClick(Sender: TObject);
    procedure ButtonInsertClick(Sender: TObject);
    procedure ButtonChangeClick(Sender: TObject);
    procedure ButtonDeleteClick(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation
var
  Name: String;
{$R *.dfm}

procedure TForm1.ButtonSelectClick(Sender: TObject);
begin
  Name:=Edit1.Text;
  Query1.Close;  //修改SQL语句之前先关闭Query控件
  Query1.SQL.Clear; //清除旧的SQL语句
  //下面添加新的SQL语句
  Query1.SQL.Add('select * from animals.dbf');
  Query1.SQL.Add('where name=:name');//动态SQL语句
  Query1.ParamByName('name').AsString:=Name;//传递参数
  Query1.Open;  //执行新的SQL语句
  if Query1.RecordCount=0 then
    ShowMessage('没有这条记录');
end;

procedure TForm1.ButtonInsertClick(Sender: TObject);
begin
  Name:=Edit1.Text;
  Query1.Close;  //修改SQL语句之前先关闭Query控件
  Query1.SQL.Clear; //清除旧的SQL语句
  //下面添加新的SQL语句
  Query1.SQL.Add('insert into animals.dbf');
  Query1.SQL.Add('(name)');
  Query1.SQL.Add('values(:name)'); //动态SQL语句
  Query1.ParamByName('name').AsString:=Name;//传递参数
  Query1.ExecSQL;  //执行新的SQL语句
  //下面显示插入的结果
  Query1.Close;  //修改SQL语句之前先关闭Query控件
  Query1.SQL.Clear; //清除旧的SQL语句
  Query1.SQL.Add('select * from animals.dbf');
  Query1.Open;  //执行新的SQL语句
end;

procedure TForm1.ButtonChangeClick(Sender: TObject);
begin
  Name:=Edit1.Text;
  //执行查询
  Query1.Close;  //修改SQL语句之前先关闭Query控件
  Query1.SQL.Clear; //清除旧的SQL语句
  //下面添加新的SQL语句
  Query1.SQL.Add('select * from animals.dbf');
  Query1.SQL.Add('where name=:name');//动态SQL语句
  Query1.ParamByName('name').AsString:=Name;//传递参数
  Query1.Open;  //执行新的SQL语句
  if Query1.RecordCount=0 then
    ShowMessage('没有这条记录')
  else begin
    //更新指定的记录
    Query1.Close;  //修改SQL语句之前先关闭Query控件
    Query1.SQL.Clear; //清除旧的SQL语句
    //下面添加新的SQL语句
    Query1.SQL.Add('update animals.dbf');
    Query1.SQL.Add('set name=''New Name''');
    Query1.SQL.Add('where name=:name'); //动态SQL语句
    Query1.ParamByName('name').AsString:=Name;//传递参数
    Query1.ExecSQL;  //执行新的SQL语句
    //下面显示更新的结果
    Query1.Close;  //修改SQL语句之前先关闭Query控件
    Query1.SQL.Clear; //清除旧的SQL语句
    Query1.SQL.Add('select * from animals.dbf');
    Query1.Open;  //执行新的SQL语句
  end;
end;

procedure TForm1.ButtonDeleteClick(Sender: TObject);
begin
  Name:=Edit1.Text;
  //执行查询
  Query1.Close;  //修改SQL语句之前先关闭Query控件
  Query1.SQL.Clear; //清除旧的SQL语句
  //下面添加新的SQL语句
  Query1.SQL.Add('select * from animals.dbf');
  Query1.SQL.Add('where name=:name');//动态SQL语句
  Query1.ParamByName('name').AsString:=Name;//传递参数
  Query1.Open;  //执行新的SQL语句
  if Query1.RecordCount=0 then
    ShowMessage('没有这条记录')
  else if MessageDlg('确定要删除吗？',mtConfirmation,[mbYes, mbNo],0) = mrYes then
  begin
    //确认后删除
    Query1.Close;  //修改SQL语句之前先关闭Query控件
    Query1.SQL.Clear; //清除旧的SQL语句
    //下面添加新的SQL语句
    Query1.SQL.Add('delete from animals.dbf');
    Query1.SQL.Add('where name=:name');//动态SQL语句
    Query1.ParamByName('name').AsString:=Name;//传递参数
    Query1.ExecSQL;  //执行新的SQL语句
    //下面显示删除的结果
    Query1.Close;  //修改SQL语句之前先关闭Query控件
    Query1.SQL.Clear; //清除旧的SQL语句
    Query1.SQL.Add('select * from animals.dbf');
    Query1.Open;  //执行新的SQL语句
  end;
end;

end.