具有多个Join和选定列的示例LINQ

var dbRegCourses = (from a in db.CourseRegistries
                    join b in db.Courses on a.courseid equals b.id
                    join c in db.aspnet_Users on a.userid equals c.UserId
                    where a.userid == sUserID
                    orderby a.regdate, b.code, b.description,
                            b.instructor, b.date, b.venue
                    select new
                    {
                      a.regdate, b.code, b.description,
                      b.instructor, b.date, b.venue});

if (dbRegCourses.Count() > 0)
{
    ResultLbl.Text = "We found that you are registered to: " +     
                      dbRegCourses.Count().ToString() + " Courses.";
    return;
}

如果您注意到的话，这里我们使用where语句连接三个表，然后从至少两个表中选择列。