[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.


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