linq to tntity多表查询,该怎么解决

linq to tntity多表查询
linq to tntity多表查询条件在多表中都有怎么写啊比如：

select * from [user] join userdepartment on [user].user_userdepartmentid = userdepartment.userdepartment_id 
 join usergroup on usergroup_userid = user_id 
 join [group] on group_id = usergroup_groupid 
 where user_name = 'andy' or userdepartment='123' and group_name='213456'

怎么改成linq to entity啊

[解决办法]

C# code

var query=from u in user          join up in userdepartment on u.user_userdepartmentid equals up.userdepartment_id          join ug in usergroup on ug.usergroup_userid equals u.user_id          join g in group on g.group_id equals ug.usergroup_groupid          where u.suer_name=="andy" || up.userdepartment=="123" || g.group_name=="213456"          select new {u,up,ug,g};
[解决办法]
建好主外键关系后，直接 var data=from a in context.as
                            from b  in context.bs
                             select a;