unit13.pas

本例是用delphi开发的学生与课程信息管理系统

unit Unit13;

interface

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

type
  TFormsc_upd = class(TForm)
    DataSourcesc_upd: TDataSource;
    DBGridsc_upd: TDBGrid;
    Button1: TButton;
    Button2: TButton;
    Button3: TButton;
    Button5: TButton;
    GroupBox1: TGroupBox;
    Label2: TLabel;
    Editcno: TEdit;
    Button4: TButton;
    Button6: TButton;
    ADOQuerysc_upd: TADOQuery;
     
    procedure Button1Click(Sender: TObject);
    procedure DBGridsc_updCellClick(Column: TColumn);
    procedure Button6Click(Sender: TObject);
    procedure Button4Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Formsc_upd: TFormsc_upd;

implementation

{$R *.dfm}uses unit12;



procedure TFormsc_upd.Button1Click(Sender: TObject);
begin
      adoquerysc_upd.close;
      adoquerysc_upd.sql.clear;
      adoquerysc_upd.sql.add('select cno,cname,cbook');
      adoquerysc_upd.sql.add('from course where sem='''+sem+'''');
      adoquerysc_upd.sql.add('order by cno');
      adoquerysc_upd.open;

end;

procedure TFormsc_upd.DBGridsc_updCellClick(Column: TColumn);
begin
  editcno.text:=dbgridsc_upd.fields[0].asstring;
end;

procedure TFormsc_upd.Button6Click(Sender: TObject);
begin
  close;
end;

procedure TFormsc_upd.Button4Click(Sender: TObject);
var
  cno,temp:string;
begin
  cno:=editcno.text;
  if cno='' then
    showmessage('请点击或输入所选课程号！')
  else
    begin
      adoquerysc_upd.close;
      adoquerysc_upd.sql.clear;
      adoquerysc_upd.sql.text:='select cno from course where cno='''+cno+''' and sem='''+sem+'''';
      adoquerysc_upd.open;
      temp:=adoquerysc_upd.fieldbyname('cno').asstring;
      if temp=''then
        showmessage('您所选的课程不存在！')
      else
        begin
          
          adoquerysc_upd.close;
          adoquerysc_upd.sql.clear;
          adoquerysc_upd.sql.add('select sc.cno,course.cname,course.cbook from sc,course');
          adoquerysc_upd.sql.add('where sc.sno='''+sno+''' and sc.cno='''+cno+'''and sc.cno=course.cno');
          adoquerysc_upd.open;
          temp:=adoquerysc_upd.fieldbyname('cno').asstring;
          if temp<>'' then
            showmessage('您已选这个课程！')
            else
             begin
               adoquerysc_upd.close;
               adoquerysc_upd.sql.clear;
               adoquerysc_upd.sql.add('insert into sc values('''+sno+''','''+cno+''',null)');
               adoquerysc_upd.execsql;

               adoquerysc_upd.close;
               adoquerysc_upd.sql.clear;
               adoquerysc_upd.sql.add('select sno from sc where sno='''+sno+''' and cno='''+cno+'''');
               adoquerysc_upd.open;
               temp:=adoquerysc_upd.fieldbyname('sno').asstring;
               if temp='' then
                 showmessage('选课未成功！')
               else
               dbgridsc_upd.visible:=false;
               showmessage('选课成功！');
             end;
            dbgridsc_upd.visible:=true;
            adoquerysc_upd.close;
            adoquerysc_upd.sql.clear;
            adoquerysc_upd.sql.add('select cno,cname,cbook');
            adoquerysc_upd.sql.add('from course where sem='''+sem+'''');
            adoquerysc_upd.open;
        end;
    end;
end;

end.