[R] Using extract function for dates in sqldf
Michael.Laviolette at dhhs.state.nh.us
Michael.Laviolette at dhhs.state.nh.us
Wed Mar 21 16:31:27 CET 2012
I'm trying to use sqldf to query for the earliest date of a blood test when
patients have had multiple tests in a given year. My query looks like this:
test11 <- sqldf("select CHILD_ID, min(SAMP_DATE)
from lab
group by CHILD_ID
having extract (year from SAMP_DATE) = 2011")
SAMP_DATE has class "date." I get the error message
Error in sqliteExecStatement(con, statement, bind.data) :
RS-DBI driver: (error in statement: near "from": syntax error)
The problem seems to be in the second "from" where the "extract" function
is called. Does this need a fix or am I doing something wrong?
Thanks in advance and apologies if it turns out a simple error.
-M.L.
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