Increment a numeric field by one, via a direct SQL update.
This method is used primarily for maintaining counter_cache columns that are used to store aggregate values. For example, a DiscussionBoard may cache posts_count and comments_count to avoid running an SQL query to calculate the number of posts and comments there are, each time it is displayed.
counter_name - The name of the field that should be incremented.
id - The id of the object that should be incremented or an Array of ids.
# Increment the post_count column for the record with an id of 5 DiscussionBoard.increment_counter(:post_count, 5)
# File activerecord/lib/active_record/counter_cache.rb, line 103 def increment_counter(counter_name, id) update_counters(id, counter_name => 1) end