Which is the most used name? - ruby

Question

I am working on a ruby on rails site and I want to check its database for which is the most frequent name among the registered users.
There is a row called "First Name" for which I will go through. I don't mind about case sensitive right now.
Any convenient way to for example check what is the most popular name and then the second most popular, the third most popular and so on?
What I thought of is to get all users in an array and then do #users.each do |user|, then record the names in an array and after that to count the duplicates of each record that has more than one element recorded. I am not sure if its the proper way though.

Answer 1

Here is how you can do it using ActiveRecord:
User.group(:first_name).order('popularity desc').pluck(:first_name, 'count(*) as popularity')
This code translates to the SQL:
SELECT "users.first_name", count(*) as popularity FROM "users"
GROUP BY first_name
ORDER BY popularity
and you get something like:
[["John", 2345], ["James", 1986], ["Sam", 1835], ...]
If you want only the top ten names, you can limit the number of results simply by adding limit:
User.group(:first_name).order('popularity desc').limit(10).pluck(:first_name, 'count(*) as popularity')
Another option is to use the count API:
User.group(:first_name).count
=> {"Sam" => 1835, "Stefanos" => 2, ...}
# ordered
User.group(:first_name).order('count_all desc').count
=> {"John" => 2345, "James" => 1986, "Sam" => 1835, ...}
# top 3
User.group(:first_name).order('count_all desc').limit(3).count
=> {"John" => 2345, "James" => 1986, "Sam" => 1835 }

Answer 2

You could do the following SQL statement
select count(*) as count from users group by users.first_name order by count desc
Will return you the top most results. As Boris said, using just sql is the right way to go here.
Otherwise if you want to load all the users, you could do so by map-reduce.
#users.group_by(&:first_name).sort(&:count).reverse
Will give you an array of users sorted descending by their names.

Answer 3

Another way using ActiveRecord:
User.group(:first_name).count
Generated SQL is:
SELECT COUNT(*) AS count_all, name AS name FROM `users` GROUP BY name
Will output a hash of { name => number_of_occurances } e.g
{"John" => 29, "Peter" => 87, "Sarah" => 2}