varm=cn.QueryFirstOrDefault<dc_platform_balance>($"select * from dc_platform_balance where platformcode='{item.platformcode}' and currency='{item.currency}' and delstatus=0 and `day` <'{item.day.ToString("yyyy-MM-dd")}' order by day desc limit 1");
varm=cn.QueryFirstOrDefault<dc_platform_balance>($"select * from dc_platform_balance where account='{item.account}' and platformcode='{item.platformcode}' and currency='{item.currency}' and delstatus=0 and `day` <'{item.day.ToString("yyyy-MM-dd")}' order by day desc limit 1");