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From: dmg <dmg@turingmachine.org>
To: emacs-orgmode <emacs-orgmode@gnu.org>
Subject: wishful thinking: using SQL to process tables. in the meantime, use R
Date: Wed, 20 Jul 2016 18:13:53 -0700	[thread overview]
Message-ID: <CAEBXXD83z0sVsJpv7641esLmFAzh4-PX2foEMs41o1HP0aGAsw@mail.gmail.com> (raw)

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Hi everybody,

I was wondering if there was a way to join two tables given
a common column. I searched but found nothing.

it would be awesome to be able to process tables in SQLITE.
something like this:

#+BEGIN_SRC sqlite :var a=table1 b=table2  :colnames yes
  select * from $a join $b using column;
#+END_SRC

I think it is not that hard. The infrastructure is there already.
It is just a matter of creating temp tables (this is the major part missing
which implies making a create statement from the table, but given
that sqlite is very type agnostic, it might not be hard),
load them from the CSV files
the execute the block. A db parameter might be needed
for a scratch database file, but it could be a temporary one if
none is provided.

But in the meantime, it occurred to me, it is simple in R to do the join
and might be useful to others:

#+BEGIN_SRC R :var a=table1 b=table2 :results value :colnames yes
merge(a,b,by.x="column")
#+END_SRC

merge can do left joins, right joins, full joins, joins,

https://stat.ethz.ch/R-manual/R-devel/library/base/html/merge.html

but there is nothing like the power of SQL to process tables, though.

-- 
--dmg

---
Daniel M. German
http://turingmachine.org

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next             reply	other threads:[~2016-07-21  1:14 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-07-21  1:13 dmg [this message]
2016-07-21 17:35 ` wishful thinking: using SQL to process tables. in the meantime, use R Thierry Banel

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