Mysql常用函数的汇总,可看下面文章
https://cloud.tencent.com/developer/article/1641021
返回参数的符号
SIGN(X)
SELECT SIGN(-32); # -1 SELECT SIGN(0); # 0 SELECT SIGN(234); # 1 SELECT SIGN("-1s"); # -1 SELECT SIGN("1s1"); # 1 SELECT SIGN("中文"); # 0