Hi Works #1
I tought GROUP BY was a grouping algo not a summarizing instruction. I have problems understanding the meaning of INNER, LEFT etc. Does LEFT mean that the joined table will be placed before the actual table ? meaning that calculations will be made against the joined table first ? Could you esplain these terms a bit to me please ? I think these terms are the most ambigous to the beginners like me. I read the documentation but I'm not sure I understand it very well. Thanks Sandy > Here is how I prefer to write the query you wrote (using an explicit JOIN) > > SELECT livres.* > , auteurs.id as auid > , CONCAT(auteurs.nom,', ',auteurs.prenom) as nomauteur > FROM livres > INNER JOIN auteurs > ON auteurs.id = livres.auteur > ORDER BY livres.titre; > > That would find all books with auteurs, however it would not locate any > books without auteurs. To list all books regardless of whether they have a > matching auteur, you need to use one of the OUTER joins like this: > > SELECT livres.* > , auteurs.id as auid > , CONCAT(auteurs.nom,', ',auteurs.prenom) as nomauteur > FROM livres > LEFT JOIN auteurs > ON auteurs.id = livres.auteur > ORDER BY livres.titre; > > > That will list every book and any auteurs should they exist. Please let me > know if this gets you going. > > Shawn Green > Database Administrator > Unimin Corporation - Spruce Pine > > -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED]
