mysql默认是不能自定义函数的
当create function时
This function has none of DETERMINISTIC, NO SQL, or READS SQL DATA in its declaration and binary
solution 1:
exec：
SET GLOBAL log_bin_trust_function_creators = 1;
mysql重启会失效
attention：mysql主从数据库配置，主从复制时，从机必须要设置，不然会导致主从同步失败
solution 2：
配置my.cnf
log-bin-trust-function-creators=1
重启mysql服务