我在DolphinDB database GUI中执行下列代码:
tb=table(2001..2012 as yearOfRegistration,1..12 as monthOfRegistration)
select string(yearOfRegistration) + "." + string(monthOfRegistration) + ".01" as newcat from tb
结果正常,如下:
但改成:
select date(string(yearOfRegistration) + "." + string(monthOfRegistration) + ".01") as newcat from tb
执行后结果如下图,看了下,月份是一位数的,都变成空值了,为啥?
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