fast_course_item_serializer.rb

    sql = "SELECT courses.id as 'course_id',
            courses.name as 'name',
            courses.likes as 'likes',
            courses.duration as 'time_total',
            completions.finished    as 'completed',
            completions.finished_at as 'completed_on',
            COALESCE(completions.duration,0) as 'time_remaining',
            essentials.id as 'essential_id',
            electives.id as 'elective_id',
            electives.points as 'total_points',
            CASE
              WHEN completions.finished THEN electives.points
              WHEN COALESCE(completions.duration, 0) = 0 THEN 0
              ELSE NULL
           END AS 'current_points',
           COALESCE(completions.duration / courses.duration, 0) as 'percent_complete'
     FROM courses
     LEFT JOIN completions ON courses.id = completions.completable_id
                           AND completions.completable_type = 'Course'
                           AND completions.user_id = #{user.id}
     LEFT JOIN electives ON electives.course_id = courses.id and electives.certification_id = #{cert_id}
     LEFT JOIN essentials ON essentials.course_id = courses.id
     LEFT JOIN terms ON terms.certification_id = #{cert_id} and essentials.term_id = terms.id
     WHERE courses.id IN (#{course_ids.join(",")})
     AND COALESCE(essentials.term_id,0) = COALESCE(terms.id,0)
    "
    results = Course.connection.select_all(sql)