select sum(amount),sum(card_number) from sy_user inner join sy_admin on sy_user.customer_id=sy_admin.admin_id inner join sy_user_charge_log on sy_user.username=sy_user_charge_log.username where status = 1 and customer_id = 2;

三表联查，这是我目前写过的最长的sql语句，嗯嗯，果然遇到问题才能让我更快成长，更复杂的语句也有了一些心得了