unit4.~pas

是关于SQL的一些程序 很好很经典的~大家又兴趣的可以学习下

unit Unit4;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;

type
  TSearchUserForm = class(TForm)
    Checkname: TCheckBox;
    Edit1: TEdit;
    Checkpower: TCheckBox;
    powertype: TComboBox;
    Search: TButton;
    Button1: TButton;
    procedure SearchClick(Sender: TObject);
    procedure oninit();
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  SearchUserForm: TSearchUserForm;

implementation

{$R *.dfm}
uses unit2,Unit3;
Procedure TSearchUserForm.oninit();
begin
  with mydata.Query_power do//使用Query_power进行查询
  begin
    close;
    with  sql do //设置SQL属性
    begin
      clear;
      add('select * from 权限表');//获取权限表中的所有资料
    end;
    open;
    powertype.Clear; //combo box清空
    while eof=false do
    begin
      //循环获取权限中的所有资料，并将它们添加到combo box中
      powertype.items.Append(FieldByName('权限名').asstring);
      next;
    end;
  end;
end;
procedure TSearchUserForm.SearchClick(Sender: TObject);
var sign:boolean;
begin
  sign:=false;//用来标志是否有查询条件
   with mydata.Query1 do //使用Query1进行数据库操作
   begin
    close;
    with  sql do
    begin
      clear;
      add('select * from 用户密码表');
      if checkname.Checked then //当选择用户名查询
      begin
        add(' where 用户名=:name');
        //用参数化方法添加SQL语句
        ParamByName('name').AsString:=trim(Edit1.Text);
        sign:=true;
      end;
      if  checkpower.Checked  then //当选择权限查询
      begin
        if  sign  then//判断是否进行了用户名查询，分别进行不周处理
        begin
          add(' and 权限类型=:power');
        end else
        begin
          add(' where 权限类型=:power');
        end;
        //给参数赋值
        ParamByName('power').AsString:=trim(powertype.Text);
      end;
    end;
    open;
   end;
   //执行主界面的初始化函数，更新数据
   main.oninit();
   close;
end;

procedure TSearchUserForm.Button1Click(Sender: TObject);
begin
  close;
end;

end.