[R] question on sqldf syntax

[Gabor Grothendieck]

On Mon, Jan 25, 2010 at 2:17 PM, GL <pflugg at shands.ufl.edu> wrote:
>
> trying to structure sql to merge two datasets. structure follows:
>
> dbs.possible.combos (all possible combinations of dates and places)
> Date Place
> 1/1/10 N-01
> 1/1/10 S-02
> 1/2/10 N-01
> 1/2/10 S-02
> etc...
>
> dbs.aggregate (the raw data aggregated by date and location)
> Date Place Days
> 1/1/10 N-01 6
> 1/1/10 S-02 10
> 1/2/10 S-02 5
>
>
> Trying to merge so I look-up the values for each possible combo
> dbs.final <- sqldf("select dbs.possible.combos$Date,
> dbs.possible.combos$Place, dbs.possible.combos$Days FROM dbs.possible.combos
> LEFT JOIN dbs.aggregate ON (dbs.possible.combos$Place = dbs.aggregate$Place)
> AND (dbs.possible.combos$Date = dbs.aggregate$Date)")
>
> Resulting in:
> Error in sqliteExecStatement(con, statement, bind.data) :
>  RS-DBI driver: (error in statement: near ".": syntax error)
>
> What am I getting wrong in the syntax?

You have to pass it a valid SQL statement but $ is not an SQL
operator.  Also dot (.) is an SQL operator so you have quote
identifiers that contain a dot so that it will not regard those dots
as operators.

Try this:

library(sqldf)

lines1 <- "Date Place
1/1/10 N-01
1/1/10 S-02
1/2/10 N-01
1/2/10 S-02"
dbs.possible.combos <-
   read.table(textConnection(lines1), header = TRUE, as.is = TRUE)

lines2 <- "Date Place Days
1/1/10 N-01 6
1/1/10 S-02 10
1/2/10 S-02 5"
dbs.aggregate <- read.table(textConnection(lines2), header = TRUE, as.is = TRUE)

dbs.final <- sqldf('select Date, Place, Days
	FROM "dbs.possible.combos"
	LEFT JOIN "dbs.aggregate" using (Place, Date)')

Giving:

> dbs.final
    Date Place Days
1 1/1/10  N-01    6
2 1/1/10  S-02   10
3 1/2/10  N-01   NA
4 1/2/10  S-02    5