qcam/rails-active_query.md

## rails-active_query.md

      
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              rails-active_query.md
            
          
    Rails Active Record Query

INNER JOIN
Category.joins(:posts)

# SELECT categories.* FROM categories INNER JOIN posts ON posts.category_id = categories.id
LEFT OUTER JOIN
Client.includes("orders").where(first_name: 'Ryan', orders: { status: 'received' })

# SELECT count(DISTINCT clients.id) AS count_all FROM clients
# LEFT OUTER JOIN orders ON orders.client_id = client.id WHERE
# (clients.first_name = 'Ryan' AND orders.status = 'received')