185 MySQL中TIMESTAMPDIFF和TIMESTAMPADD函数的用法

https://blog.youkuaiyun.com/zmxiangde_88/article/details/8011661   

SQL里面怎么用呢

TIMESTAMPDIFF(DAY, '" . date('Y-m-d', $nowtime) . "', from_unixtime(birthday_time, '%Y-%m-%d')) = 1

生日的前一天发短信，送祝福