Multiple SQL joins

Question

I need to execute a query To retrieve data from multiple tables but I m rather confused on how to do it all at once    Books   ISBN   BookTitle  Edition  Year  PublisherID  Pages  Rating Categories   CategoryID  Category Categories Books   Categories Category ID   Books ISBN Publishers   Publisherid  Publisher Writers   WriterID  LastName Writers Books   Writers WriterID   Books ISBN   Categories Books and Writers Books are the intermediate tables to help me implement many to many relationships between the tables    I need a single query with multiple joins to select    Title  Edition  Year  Pages  Rating from Books Category from Categories Publisher from Publishers LastName from Writers

User · Answer

You can use something like this    SELECT     Books BookTitle      Books Edition      Books Year      Books Pages      Books Rating      Categories Category      Publishers Publisher      Writers LastName FROM Books INNER JOIN Categories Books ON Categories Books  Books ISBN   Books  ISBN INNER JOIN Categories ON Categories  CategoryID   Categories Books  Categories Category ID INNER JOIN Publishers ON Publishers  Publisherid   Books PublisherID INNER JOIN Writers Books ON Writers Books  Books ISBN   Books  ISBN INNER JOIN Writers ON Writers Writers Books    Writers WriterID

User · Answer

SELECT  B Title  B Edition  B Year  B Pages  B Rating     --from Books   C Category                                        --from Categories   P Publisher                                       --from Publishers   W LastName                                        --from Writers  FROM Books B  JOIN Categories Books CB ON B  ISBN   CB  Books ISBN JOIN Categories Books CB ON CB   Categories Category ID   C  CategoryID JOIN Publishers P ON B PublisherID   P  Publisherid JOIN Writers Books WB ON B  ISBN   WB  Books ISBN JOIN Writers W ON WB  Writers WriterID   W  WriterID

User · Answer

It will be something like this   SELECT b Title  b Edition  b Year  b Pages  b Rating  c Category  p Publisher  w LastName FROM     Books b     JOIN Categories Book cb ON cb  ISBN   b  Books ISBN     JOIN Category c ON c  CategoryID   cb  Categories Category ID     JOIN Publishers p ON p  PublisherID   b PublisherID     JOIN Writers Books wb ON wb  Books ISBN   b  ISBN     JOIN Writer w ON w  WritersID   wb  Writers WriterID   You use the join statement to indicate which fields from table A map to table B  I m using aliases here thats why you see Books b the Books table will be referred to as b in the rest of the query  This makes for less typing   FYI your naming convention is very strange  I would expect it to be more like this   Book  ID  ISBN   BookTitle  Edition  Year  PublisherID  Pages  Rating Category  ID   Name  BookCategory  ID  CategoryID  BookID Publisher  ID   Name  Writer  ID  LastName BookWriter  ID  WriterID  BookID

[sql] Multiple SQL joins

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