[R-sig-DB] Opening multiple result sets
Seth Falcon
@|@|con @end|ng |rom |hcrc@org
Sun Jul 15 23:57:10 CEST 2007
"Paul Dlug" <paul.dlug using gmail.com> writes:
> 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:
The RMySQL sources contain the following comment:
/* Do we have a pending resultSet in the current connection?
* MySQL only allows one resultSet per connection.
*/
So I don't think you can do that. You could try:
- opening more than one connection
- using a subselect. I'm not certain that MySQL supports this, but
you can try: SELECT ... from (SELECT ... from ...) WHERE ...
> 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.
Perhaps another workaround might be LIMIT and OFFSET?
+ seth
--
Seth Falcon | Computational Biology | Fred Hutchinson Cancer Research Center
http://bioconductor.org
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