Re: Telling how many records are joined

It sounds like you want unique papercode items right?

Thats what distinct keyword is for:

SELECT distinct 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;

Also a another trick you can include just those having a count of more
than one:

SELECT distinct 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 HAVING count(papercode) > 0;

- Bill

Andrew Perrin wrote:

>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 times the 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:
>
>
>
>Thanks for any advice.
>
>----------------------------------------------------------------------
>Andrew J Perrin - andrew_perrin(at)unc(dot)edu - http://www.unc.edu/~aperrin
> Assistant Professor of Sociology, U of North Carolina, Chapel Hill
> 269 Hamilton Hall, CB#3210, Chapel Hill, NC 27599-3210 USA
>
>
>
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