On 22/02/2008, Zbigniew Lukasiak <[EMAIL PROTECTED]> wrote: > > On Fri, Feb 22, 2008 at 4:26 PM, Dermot <[EMAIL PROTECTED]> wrote: > > > > > >There is a section about making 3 tables with SQLite3; books, authors > and > > > book_authors. The last table is described as > > > >'book_authors' is a many-to-many join table between books & authors' > > > > > > > >My query is: Is this the "best practise" or an over-simplification > for us > > > newbies? Would you normally create a table for >joins to show many to > many > > > relationships? I would have though that you could use SQL statements > to > > > retreive that rather >than create a table of it. > > > > > > > > > To answer your question, yes, you need a join table. Each record in it > > > expresses a relationship between a record in table A and a record in > table > > > B. > > > > > > I'd recommend working through an SQL book that explains SQL concepts > in > > more > > > detail as that really is a prerequisite for using a database or DBIC > > > effectively. > > > E.g. http://tinyurl.com/ywdxfu > > > > > > > > I am unsettled by this. I went and re-read chapter 4 of the book I do > have > > (learning MYSQL) on database design and modelling. I still can't see the > > value in creating a separate table for a join. > > > > If you have a 1:N table of authors and a table of books with the author > ID > > as a foreign key, surely that all you need to create any join you might > > want. I know sqlite3 doesn't understand foreign keys but DBIC can create > > them for you. Isn't that where the relationship is established? > > > The standard technique with a joining table is for the case when you > can have multiple authors on the book (hence the name many to many) - > you cannot store all of them in one field. If all you need is a 1:N > relationship then you are ok without the linking table.
Is this "joining table" different from a SQL VIEW? Dp.
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