python mysql pymysql where 当多条件查询，动态出现某些查询条件为空，就不作为条件查询的情况 转载：https://blog.csdn.net/weixin_45337377/article/details/106307341?utm_medium=distribute.pc_relevant.none-task-blog-BlogCommendFromMachineLearnPai2-3.channel_param&depth_1-utm_source=distribute.pc_relevant.none-task-blog-BlogCommendFromMachineLearnPai2-3.channel_param