DolphinDB中DATE默认格式是yyyy.MM.dd,如2020.01.01,如不符合这个格式,需要用datetimeParse进行转换。代码改为如下:
select temporalParse(string(yearOfRegistration) + "." + string(monthOfRegistration) + ".01","yyyy.M.dd") as newcat from tb
或者从MONTH类型转换为DATE:
select date(1970.01M+(yearOfRegistration-1970)*12+monthOfRegistration-1) from tb