How to sort on start_time?

I don't agree to the solution of the teacher. I remember from my school time, what a schedule should look like. First each class has a number, so I used the pk of the classes table. Then a schedule contains the class name and the teacher. Of course it needs to have the start time, and room number, so we know when and where to go. And the schedule of course needs to be sorted by time.

The problem I'm facing is that the periods table stores the START_TIME as text.

I can't figure out how to sort on this column.

I tried this:

SELECT
  c.id 'Class ID',
  su.name 'Class Name', 
  su.grade 'Grade',
  t.first_name || ' ' || t.last_name 'Teacher',
  CASE WHEN LENGTH(p.start_time) = 5 THEN TIME(p.start_time)
    ELSE TIME('0' || p.start_time) END 'Start Time',
  r.id 'Room Number' 
FROM classes c
INNER JOIN schedule sc ON c.id = sc.class_id
INNER JOIN students st ON sc.student_id = st.id
INNER JOIN teachers t ON c.teacher_id = t.id
INNER JOIN subjects su ON c.subject_id = su.id
INNER JOIN periods p ON c.period_id = p.id
INNER JOIN rooms r ON c.room_id = r.id
WHERE st.first_name = 'Rex' AND st.last_name = 'Rios'
ORDER BY 'Start Time'

But it delivers unexpected results in the sorting of the 'Start Time' column. I know the result would still be incorrect, as AM and PM information is also missing.

But still I would expect from my query to get times sorted as

• 01:15:00
  
• 02:05:00
• 09:05:00
• 09:55:00
• 10:44:00
• 11:35:00
• 12:25:00

How to solve this?