exercism.io

https://github.com/exercism/exercism.io

Ruby

Quickly ramp up in new programming languages.

ParticipationStats#sql

Subselect: For each period, select one row per user with user comment count
           and comment lengths.
Then condense the results down to one row per period, aggregating all the
results using comma-separated lists.

Source | Google | Stack overflow

Edit

git clone [email protected]:exercism/exercism.io.git

cd exercism.io

open lib/exercism/participation_stats.rb

Contribute

# Make a new branch

git checkout -b -your-name--update-docs-ParticipationStats-sql-for-pr

# Commit to git

git add lib/exercism/participation_stats.rbgit commit -m "better docs for ParticipationStats#sql"

# Open pull request

gem install hub # on a mac you can `brew install hub`

hub fork

git push <your name> -your-name--update-docs-ParticipationStats-sql-for-pr

hub pull-request

# Celebrate!