ObjectQuery支持HQL的各种Join操作，例如下列的HQL：
from Eg.Cat as cat
inner join cat.Mate as mate
left outer join cat.Kittens as kitten
from Eg.Cat as cat left join cat.Mate.Kittens as kittens
from Formula form full join form.Parameter param用ObjectQuery可以这样写：
| Query.From(DB.Cat |
| .InnerJoin(DB.Mate, DB.Cat.Mate) |
| .LeftOuterJoin(DB.Kitten, DB.Cat.Kittens)) |
| Query.From(DB.Cat.LeftJoin(DB.Kitten, DB.Cat.Mate.Kittens)) |
| Query.From(DB.Formula.FullJoin(DB.Parameter, DB.Formula.Parameter)) |
支持的Joins类型有：
-
inner join
-
left outer join
-
right outer join
-
full join (not usually useful)
