[R] Connecting to database on statup

Prof Brian Ripley ripley at stats.ox.ac.uk
Sat Aug 11 16:47:55 CEST 2007

On Sat, 11 Aug 2007, Ruddy M wrote:

> Hello,
> Q/ Is it possible to create a DBMS connection automatically on startup of R? (Making sure of course that the db server has been started...)
> I am running MySQL on Mac OS X 10.4.2 with R2.4.1.
> I have tried to write a function using the RMySQL commands (below) and place them in .First of .RProfile:
> drv <- dbDriver("MySQL")
> dbcon <- dbConnect(drv, {other parameters present in my.cnf file} dbname="mydbName")
> DOES create a connection when entered into my R console individually but NOT when I place them in a function, i.e.,
> condb <- function() {
> 	drv <- dbDriver("MySQL")
> 	dbcon <- dbConnect(drv, dbname="mydbName")
> 	dbGetInfo(db)
> 	}
> When the function is called, the dbGetInfo(dbcon) does return connection 
> info but no connection object is present.

What do you think the return value of this function is?

You need to return dbcon, not the value of dbGetInfo(<some argument other 
than db>).  Perhaps you meant to print the latter?: if so you need at 
explicit print() statement.

Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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