protected void Practice_Todo()
{
string userId = Session["userId"].ToString();
string sql = "select * from PracticeInfo inner join SCInfo on PracticeInfo.courseId = SCInfo.CourseId inner join CourseInfo on CourseInfo.courseId = SCInfo.CourseId inner join VideoInfo on VideoInfo.VideoId = PracticeInfo.videoId where PracticeInfo.practiceId not in (select practiceId from AnswerResult where stuId = '" + userId + "') and SCInfo.StuId = '" + userId + "'";
TodoList.DataSource = DataOperate.GetDataset(sql, "PracticeInfo");
TodoList.DataKeyNames = new string[] { "practiceId" };
TodoList.DataBind();
}