various refactoring
various refactoring

sunjian1/mysql,helight/helight_code,jockchou/mysql,helight/helight_code,methane/mysql,segmentio/mysql,beego/mysql,siriele/mysql,cw2018/mysql,rlowe/mysql,helight/helight_code,helight/helight_code,helight/helight_code,go-sql-driver/mysql,Frca/mysql,netroby/mysql,bookerzzz/mysql,joshuaprunier/mysql,henrylee2cn/mysql,muthusubbu459/mysql,Freeaqingme/golang-sql-driver-mysql,cxflag203/mysql,VividCortex/mysql,zhgo/mysql,eklitzke/mysql,helight/helight_code,nanata1115/mysql,LightKool/mysql-go,Vorstack/mysql,eXcomm/gomysql,helight/helight_code,segmentio/mysql,chinanjjohn2012/mysql,VividCortex/mysql,springning/mysql,LightKool/mysql-go,bookerzzz/mysql,methane/mysql,dalinaum/go-mysql-driver,hebihui/mysql,tmulchay/mysql,roth1002/mysql,hyperworks/mysql,yonglehou/mysql,rafaeljusto/mysql,helight/helight_code,yyljlyy/mysql,Go-SQL-Driver/MySQL,helight/helight_code,wfxiang08/mysql,aperera/mysql