Active Record Queries

clients = Client.find([1, 10])

SELECT * FROM clients WHERE (clients.id IN (1,10))

Client.find_by! first_name: 'Nobody'

SELECT * FROM clients WHERE
(clients.first_name = 'Nobody)
LIMIT 1

find_by! will raise an error if no record is found.
# => ActiveRecord::RecordNotFound

Client.where("orders_count = ? AND locked = ?", params[:orders], params[:locked])

Client.where("created_at >= :start_date AND created_at <= :end_date",  {start_date: params[:start_date], end_date: params[:end_date]})}

Client.where(created_at: (Time.now.midnight - 1.day)..Time.now.midnight)

SELECT FROM clients WHERE(clients.created_at
BETWEEN '2008-12-21 00:00:00'
AND '2008-12-22 00:00:00')

Subsets: Find using SQL IN

Client.where(orders_count: [1,3,5])

SELECT * FROM clients WHERE (clients.orders_count IN (1,3,5))

Client.where.not(locked: true)

SELECT * FROM clients WHERE (clients.locked != 1)

Client.select(:name).distinct

SELECT DISTINCT name FROM clients

Client.limit(5)

SELECT * FROM clients LIMIT 5

client = Client.take(2)

SELECT * FROM clients LIMIT 2

Returns record without any implicit ordering.
Returns nil if no record is found.

Client.limit(5).offset(30)

SELECT * FROM clients LIMIT 5 OFFSET 30

Client.find_or_create_by!(first_name: 'Andy')

SELECT * FROM clients WHERE(clients.first_name = 'Andy') LIMIT 1
BEGIN INSERT INTO clients(created_at, first_name, updated_at)
VALUES ('2011-08-30 05:22:57', 'Andy', '2011-08-30 05:22:57') COMMIT

nick = Client.find_or_initialize_by(first_name: 'Nick')

Client.find_by_sql("SELECT * FROM clients INNER JOIN orders ON clients.id = orders.client_id ORDER BY clients.created_at desc")

Client.exists?(1)

Client.exists?(name: ['John', 'Sergei']

Client.where(first_name: 'Ryan').exists?

Client.count

SELECT count(*) AS count_all FROM clients

Client.average("orders_count")

Client.minimum("age")

minimum/maximum value of a field

Client.sum("orders_count")

sum of a field

Client.order(:orders_count, created_at: :desc)

Client.order("orders_count ASC, created_at DESC")

Client.order("orders_count ASC").order("created_at DESC")

SELECT * FROM clients ORDER BY orders_count ASC, created_at DESC