SAS的日期时间都是数字型的，以便于计算。有各种格式可以从数值转变为字符型。1960-01-01是日期的开始，SAS的日期是0. 之后每天加一。1960-01-02的值为1. 1959-12-31的值为-1. 以此类推。时间是一秒为单位计算。从0（00：00：00）到86400（24：00：00）。每加一秒数值加一。
常用的日期时间转换的function如下：
data _null_;
a=mdy(12,31,1959);
b='02jan1960'd;
c='24:00:00't;
d='00:00:00't;
e='31dec90:5:00:00'dt;
format e datetime18.;
put a= b= c= d= e=;
run;
a=-1 b=1 c=86400 d=0 e=31DEC90:05:00:00

1# jiangh_fox


I give you some example in my real project :

The Character version of Date I`m usually encountered with looks like this "mm/dd/yyyy". What I want is to transfer this into Date9. format which could be esaily computed in SAS.

Define the Format first:



Set up the utility macro like this :




After that, you could easily call macro %dt within the rest of your program.



The date transfer issue come acrossed a lot in the clinical trial projects. I hope the above contents are making sense to you.

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