mysqli - Double INNER JOIN and SUM -

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table pckeyword kwid | keyword

table prophrase kwid | vote

table contraphrase kwid | vote

so vote column integer , want sum specified keyword this:

examplekeyword | 12 | 47

til have doesnt work correctly:

    select pckeyword.kwid, pckeyword.keyword, sum( prophrase.vote ) provotes, sum( contraphrase.vote ) contravotes pckeyword inner join prophrase on prophrase.kwid = pckeyword.kwid inner join contraphrase on contraphrase.kwid = prophrase.kwid group pckeyword.keyword order pckeyword.keyword asc

you try:

select kwid, keyword, provotes, contravotes pckeyword inner join ( select kwid pid, sum( vote ) provotes                prophrase group kwid )  p on pid = kwid inner join ( select kwid cid, sum( vote ) contravotes              contraphrase group kwid ) c on cid = kwid

this way grouping once in derived tables , not often! (by separating tables derived tables tidy whole syntax, since column names unique within each derived table expression.)

see here: http://sqlfiddle.com/#!2/70634/1

edit

just completeness, here version left joins , coalesce() make sure meaningful results cases there no votes:

select kwid, keyword,         coalesce(provotes,0) provotes,         coalesce(contravotes,0) contravotes pckeyword left join ( select kwid pid, sum( vote ) provotes                prophrase group kwid )  p on pid = kwid left join ( select kwid cid, sum( vote ) contravotes              contraphrase group kwid ) c on cid = kwid

sqlfiddle: http://sqlfiddle.com/#!2/ec51cb/1


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