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I have the following code:
@posts = Post.joins(:user).joins(:blog).select which is meant to find all posts and return them and the associated users and blogs. However, users are optional which means that the INNER JOIN that :joins generates is not returning lots of records.
How do I use this to generate a LEFT OUTER JOIN instead?
621
A left outer join (or just left join) is used to query a table based on matching and non-matching entries from a related table. Contrarily to an inner join, the left outer join will always return all the entries of the left table even if the join condition does not find any match on the right table.
LEFT JOIN SyntaxON table1.column_name = table2.column_name; Note: In some databases LEFT JOIN is called LEFT OUTER JOIN.
Left outer join includes the unmatched rows from the table which is on the left of the join clause whereas a Right outer join includes the unmatched rows from the table which is on the right of the join clause.
Different Types of SQL JOINs Here are the different types of the JOINs in SQL: (INNER) JOIN : Returns records that have matching values in both tables. LEFT (OUTER) JOIN : Returns all records from the left table, and the matched records from the right table.
@posts = Post.joins("LEFT OUTER JOIN users ON users.id = posts.user_id"). joins(:blog).select If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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