Laravel Query Builder

Raw SQL

-- Course lesson by course
select count(lession_id) from h247app_lessions where topic_id in 
(
    select topic_id from h247app_topics where course_id in
    (select course_id from h247app_courses where subject_code='tieng-anh')
)

Laravel Query Builder

  /**
     * * getLessonsCount.
     *
     * @return void
     */
    public function getLessonsCount()
    {
        return DB::table('h247app_lessions')
                ->select(DB::raw('count(*)'))
                ->whereIn('topic_id', function ($q) {
                    $q->select('topic_id')->from('h247app_topics')
                     ->whereIn('course_id', function ($q) {
                         $q->select('course_id')->from('h247app_courses')->where('subject_code', $this->subjectCode);
                     });
                })
                ->count();
    }