[R] sqldf with date (class date) variables ?

si.fu at ntlworld.com si.fu at ntlworld.com
Tue Jan 6 19:09:24 CET 2009


Hello,

I am having trouble with retrieving some data in queries involve with variables
with data type "date". See the enclosed example:

ll<-c("21DEC2006","15DEC2006")
ss<-data.frame(ll)
ss<-transform(ss,ll=as.date(as.character(ll)))
(ss)
     ll
1 17156
2 17150

tt<-sqldf("select ll from ss")

(tt)
>
  ll
1 NA
2 NA

> str(ss)
'data.frame':   2 obs. of  1 variable:
 $ ll:Class 'date'  int [1:2] 17156 17150

> str(tt)
'data.frame':   2 obs. of  1 variable:
 $ ll:Class 'date'  int [1:2] NA NA

So all the elements of ll (of tt) has been converted into NA. Is there anyway that I can query the variables with "date" data type using sqldf?


Many Thanks,

Si.



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