procedure Tfrm_dm.DataModuleCreate(Sender: TObject);//窗体模块先创建
var ini,iniW:tinifile;
  state:boolean;
 Cstring:ansistring;
  str,str1:ansistring;
begin
  ini:=tinifile.Create(changefileext(application.exename,'.ini'));
  state:=ini.readbool('database','connection',false);
  if not state then//数据库连接没有成功
    try
    f_config:=tf_config.create(application);//动态创建服务器配置窗体
    f_config.showmodal;
    except
    on e:exception do
    application.showexception(e);
    end;
    cstring:='provider=sqloledb.1;integrate security=sspi;persist security info=false; initial catalog=';
    str:=ini.readstring('database','initial catalog','student_info');//从配置文件中度曲数据库名字符串
    cstring:=cstring+str;
    str1:=ini.readstring('database','data sourse','microsof-b30447');//读服务器名
    cstring:=cstring+';data source=';
    cstring:=cstring+str1;
    cnn.connected:=false;
    cnn.connectionstring:=cstring;
    try
      cnn.connected:=true;
    except
      application.messagebox('与数据库服务器连接未成功，请重新配置','警告对话框',mb_ok);
    end;
    iniW:=tinifile.create(changefileext(application.exename,'.ini'));
    state:=cnn.connected;
    iniw.writebool('database','connection',state);//将数据库连接是否成功写入配置文件
end;


procedure Tf_config.FormCreate(Sender: TObject);//配置窗口
var filename:string;
inifile:tinifile;
begin
filename:=extractfilepath(application.ExeName)+'student_info.ini';
if not fileexists(filename) then fileclose(filecreate(filename));
end;

procedure Tf_config.RzBitBtn1Click(Sender: TObject);//确定按扭
var inifile:tinifile;
    filename:String;
begin
    if (trim(rzedit1.Text)='')or (trim(rzedit2.Text)='') then
    begin
      showmessage('请填写数据库服务器名和数据库名称！');
      exit;
      rzedit1.SetFocus;
    end;
    try
    filename:=extractfilepath(application.ExeName)+'student_info.ini';
    if not fileexists(filename) then fileclose(filecreate(filename));
    inifile:=tinifile.Create(filename);
   inifile.WriteString('database','initial catalog',rzedit2.Text);
   inifile.WriteString('database','data sourse',rzedit1.Text);
   //inifile.Free;
   except
   showmessage('连接服务器失败！');
   end;
   close;//关闭窗口
end;
按了确定按纽后程序出错"连接字符串属性无效",请问什么原因,大家有什么好的代码吗?