mysql 基础语句

1. 查询记录中created_at=0的数据 并将pay_time的值赋值到created_at，updated_at中

UPDATE `n_book_paid` k1, (SELECT id,pay_time FROM `n_book_paid` WHERE created_at=0) k2 SET k1.created_at=k2.pay_time,k1.updated_at=k2.pay_time WHERE created_at=0 AND k1.id=k2.id;