var begin_daily = from a in _postgreDbContext.tab1 join b in _postgreDbContext.tab2 on a.id equals b.merchant_id into a_left from left_a in a_left.DefaultIfEmpty() where left_a.date.ToString("yyyy-MM-dd") == begin_date select new { left_a.id, left_a.balance, left_a.service_balance, left_a.paid_money };