Greetings-
I'm sure there's a (moderately) simple answer to this, but I'd love some
help with it.
I have a database with four tables:
papers - information about newspapers, including a unique paperid
letters - information and text of letters to the editors, including a unique paperid and the paperid in which it
appeared
patterns- word patterns occurring in one or more letters, including a unique patternid
pattern_occurrences - a linking table containing a letterid, a patternid, and a count (the number of
timesthe pattern occurs in the letter).
The patterns and pattern_occurrences tables are quite large (around 3
million records each).
I'd like to know, for example, how many letters from each paper have one
or more patterns already coded. The best I can do is:
SELECT papercode, count(papercode) FROM papers, letters
WHERE papers.paperid=letters.paperid AND
letters.letterid IN (SELECT DISTINCT o_letterid FROM pattern_occurrences)
GROUP BY papercode;
Thanks for any advice.
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Andrew J Perrin - andrew_perrin@unc.edu - http://www.unc.edu/~aperrinAssistant Professor of Sociology, U of North
Carolina,Chapel Hill 269 Hamilton Hall, CB#3210, Chapel Hill, NC 27599-3210 USA
