This is a best practices / style question.
The way I use RODBC is I something like this:
foo <- sqlQuery(db, "select * from foo")
apply(foo, 1, function{...})
That is, I use apply to iterate over each result -- row -- in the
RODBC-produced dataframe. Is this how one generally wants to do this?
My concern is that when apply iterates over the rows, it uses
as.matrix() to convert the dataframe to a character representation of
itself. Thus my database's carefully planned data types (that RODBC
carefully preserved when returning query results) get completely lost as
I process the data. I've taken to judiciously sprinkling as.numeric()
and friends here and there, but this is just begging for bugs.
In other words, what is the smart way to process a dataframe by rows? Or
is there, by chance, a specific technique or practice that is available
for RODBC results but not for dataframes in general?