linq join on 多条件

借助于匿名类型：和解决按多条件分组的思路相同。

from c in CustomerLegalOrgsjoin ao in AccountingOrganizationConfigs on c.OrganizationId equals ao.OrganizationIdjoin ac in AccountingCustomerConfigs on c.CustomerLegalId equals ac.CustomerLegalIdjoin aoc in AccountingOrganizationCustomerConfigs on new{Oid=ao.Id,Cid=ac.Id} equals new{Oid =aoc.AccountingOrganizationConfigId,Cid = aoc.AccountingCustomerConfigId}