[R] SQL Primer for R
ivo welch
ivowel at gmail.com
Mon Aug 25 15:12:59 CEST 2008
Dear R wizards:
I decided to take the advice in the R data import/export manual and
want to learn how to work with SQL for large data sets. I am trying
SQLite with the DBI and RSQLite database interfaces. Speed is nice.
Alas, I am struggling to find a tutorial that is geared for the kind
of standard operations that I would want in R. Simple things:
* how to determine the number of rows in a table. (Of course, I
could select a row of data and then use this.)
* how to insert a new column into my existing SQL table---say, the
rank of another variable---and save it back. Am I supposed to create
a new data frame, then save it as a new table, then delete the old SQL
table?
* how to save a revised version of my table in a different sort order
(with or without deleting the original table). <-- I guess this is
not appropriate, as I should think of SQL tables as unordered.
I guess these would make nice little text snippets in the R Data
import/export manual, too. help appreciated.
regards,
/ivo
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