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tommich
Starting Member
4 Posts |
 Posted - 2012-01-16 : 09:04:02
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Hello,i have the following problem:show the numbers of lends for every author(give also the the authors with 0 lends)i have 3 tables:boeken(columns:boek_id,auteur_id,jaar,titel,cat_id,uitg_id),uitleen(uitlnr,boek_id,datum,klant_id)and auteur(auteur_id,naam).I've maked the follow query:select naam,COUNT(*)as uitleningenfrom AUTEUR aleft join BOEKEN b on b.auteur_id=a.auteur_id and(b.boek_id in(select boek_id from UITLEEN))group by naam It's almost ok;it gives me al the authors and the correct number of lends for the authors who have lend out a book,but for the authors who not have Lend out a book,it counts 1.What can i do for making this:0. |
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singularity
Posting Yak Master
153 Posts |
Posted - 2012-01-16 : 09:24:45
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[code]select naam, COUNT(*) count(boek_id) as uitleningenfrom AUTEUR aleft join BOEKEN b on b.auteur_id=a.auteur_id and(b.boek_id in(select boek_id from UITLEEN))group by naam[/code] |
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tommich
Starting Member
4 Posts |
Posted - 2012-01-16 : 13:08:54
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| This works,thank you very much |
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join