var query=from u in en.Products select u.OrderLine.Orders.UserName
var query=from ol in OrderLine
join o in Orders
on ol.OrderID equals o.OrderID into left1
from o in left1.DefalutIfEmpty()
join p in Products
on ol.ProductID equlas p.ProductID into left2
from p in left2.DefalutIfEmpty()
where p.price<80
select o==null?"":o.UserName;
var query = from oi in context.OrderItems
join o in context.Orders on oi.OrderId equals o.OrderId
join p in context.Products on oi.ProductId equals p.ProductId
where p.ProductId == 310
select o;
var teacher = db.Teachers.Add(new Teacher { Name = "Scott", Birthday = DateTime.Now, Sex = true });
for (int i = 1; i <= 10; i++)
{
var s = new Student { Name = "Echo·" + (char)(i + 64), Birthday = DateTime.Now, Sex = i % 2 == 1 };
teacher.Students.Add(s);
}
db.SaveChanges();
