Question

I learned that using field in (a1,a2,a3) is comparably faster than using = operator.

SELECT *
FROM user
WHERE Greeting IN ('hello', 'hi', 'hey')

How can I write above query in rails way?

Answer 1

You’d do something like this:

users = User.where('greeting in (?)', %w{hello hi hey})

Rails will know what to do with an array, %w{hello hi hey}, as a value for a placeholder. Or, if you already had an array of strings:

h_words = [ 'hello', 'hi', 'hey' ]
users   = User.where('greeting in (?)', h_words)
# or even this
users   = User.where('greeting in (:words)', :words => h_words)

or, probably the most Railsy way, like this:

users = User.where(:greeting => %w{hello hi hey})