procedure TMainForm.UniFormCreate(Sender: TObject);
begin
 FDConnection1.Connected:=true;
 FDQuery_user.Active:=true;
FDQuery_user.SQL.Text:= 'select id,user_name,password from user';
end;

 

  FDQuery1.SQL.Text :='SELECT * FROM user WHERE user_name=:user_name';
  FDQuery1.ParamByName('user_name').Value := uniedit1.Text;
  FDQuery1.Open();

  if not FDQuery1.IsEmpty then     begin      //如果用户名存在
    showmessageN( uniedit1.Text+ ' 用户名  已存在');
    exit;
  end;

  FDQuery1.SQL.Text :='insert into user values(null, :user_name, :password )';
  FDQuery1.ParamByName('user_name').AsString := uniedit1.Text;
  FDQuery1.ParamByName('password').AsString   := md5.GetHashString(UniEdit2.Text);
  FDQuery1.ExecSQL;

  FDQuery_user.Refresh;  // 显示 所有 用户