mvc 3中linq表达式两表关联

最近在使用mvc3开发项目中，遇见表和表之间关联用于查询数据，感觉很用用途，特在此整理用于记录：

1、join 关联

var data = (from a in tb_a 
                  join b in tb_b on a.字段 equals b.字段
            select a).toList();

 

2、left join (单字段关联)

var data = (from a in tb_a
                join b in tb_b on a.字段 equals b.CodeDefID
                                 into ab
                                 from bb in ab.DefaultIfEmpty()
select a).toList();

 

3、left join (多字段关联)

var data = (from a in tb_a
join b in tb_b on new { ab1 = a.a1, ab2= a.a2} equals new { ab1 = b.b1, ab2= b.b2}
                                 into ab
                                 from bb in ab.DefaultIfEmpty()

select a).toList();