[R] Reading dates in R using SQL and otherwise (and someinteresting behavior by the data editor)

Paul Miller
Thu, 08 Apr 2010 23:15:34 -0000

Hi Paul, Jim, Dennis, and others,

I got RODBC and SQL Server to create a date variable in R (see below). I'm
pretty sure the commands I was issuing before were working but that I was
stripping off the date class every time I submitted the command
"fix(mydata)." So I kept getting the mistaken impression that what I
was doing wasn't working.

One thing I've noticed is that the class for my date is of the type POSIX.
When I issue the command "head(mydata$ae_datestarted)", I get
"CDT" tacked onto my date. I'll spend some additional time
investigating this, but if an answer about how to get a class of date using my
SQL command seems obvious to someone please let me know.

Thanks,

Paul

> mydata <- sqlQuery(channel,
+ "select subject_number,
+ ae,
+ ae_ctcgrade,
+ ae_relationship,
+  ae_serious,
+ cast(ae_datestarted as datetime) as ae_datestarted,
+ ae_dateended,
+ ae_ongoing
+  from adverse_events_detail")
>
> class(mydata$ae_datestarted)
[1] "POSIXt"  "POSIXct"
> mode(mydata$ae_datestarted)
[1] "numeric"
>
> head(mydata$ae_datestarted)
[1] "2008-10-23 CDT" "2008-10-21 CDT" "2008-10-24
CDT" "2008-10-25 CDT"
[5] "2008-10-23 CDT" "2008-10-31 CDT"




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