一个主表A（a1,a2），子表B（a1,b1,b2） ，想得到的结果是 [{a1,a2,Info [{b1,b2},{b1,b2},...}]]

var list=

from a in A

join b in B on a.a1=b.a1

group b by a into g

select new {

g.key.a1,

g.key.a2,

Info=g.select (c=>new {c.b1,c.b2}).ToList()

}.tolist()