[R-sig-DB] Opening multiple result sets

Paul Dlug paul.dlug at gmail.com
Sun Jul 15 22:42:34 CEST 2007


I'm rather new to using R DBI so please excuse me if this is beyond
basic. I don't seem to be able to open more than one resultset at
time, I'm trying the following:

drv <- dbDriver("MySQL")
con <- dbConnect(drv, ...)

rs1 <- dbSendQuery(con, "SELECT ...")

while (!dbHasCompleted(rs1)) {
  data1 <- fetch(rs1, n=1)

  rs2 <- dbSendQuery(con, past("SELECT ... WHERE id =", data1$id))
  data2 <- fetch(rs2, n=1)

  dbClearResult(rs2)
}
dbClearResult(rs1)
dbDisconnect(con)


When I try to execute it I get the error:
Error in mysqlExecStatement(conn, statement, ...) :
	RS-DBI driver: (connection with pending rows, close resultSet before
continuing)

What I'm trying to accomplish is operating on the results of the first
query one row at a time and using the returned values to perform
another query and analyze the results. The first query is going to
return a large amount of data so I don't really want to fetch all rows
into memory up front, close the result set and proceed.

Any help/suggestions would be greatly appreciated.



Thanks,
Paul




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