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How to create a relationship between two tables without a match between the fields of JOIN?
Home > SQL > FAQs > How to create a relationship between two tables without a match between the fields of JOIN?
For this purpose you can use (instead of an INNER JOIN) a LEFT JOIN or a RIGHT JOIN.
In this way the data are extracted even if there is no exact match between the fields used to define the relationship.
For example:
SELECT * FROM books LEFT JOIN authors ON = libri.autore_id autori.id WHERE libri.id> 0In this case, the LEFT JOIN will show all records in the table "books" regardless of whether or not there is a correspondence with the table "authors".
To put it simple: if a book was "no author" ie "autore_id = 0" would also shown although there are no material correspondence with the table "authors" (because it has no id = 0).
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