title: Bus Timetable database design
body: <p>I'm trying to design a db to store the timetable for 300 different bus routes, 
  Each route has a different number of stops and different times for Monday-Friday, Saturday and Sunday.
  I've represented the bus departure times for each route  as follows,
  I'm not sure if i should have null values in the table, does this look ok?</p>
  
  <pre><code>route,Num,Day,    t1,   t2,   t3,    t4    t5      t6      t7      t8     t9    t10 
  
  117, 1, Monday,   9:00, 9:30, 10:50, 12:00, 14:00  18:00   19:00   null   null   null
  117, 2, Monday,   9:03, 9:33, 10:53, 12:03, 14:03  18:03   19:03   null   null   null
  117, 3, Monday,   9:06, 9:36, 10:56, 12:06, 14:06  18:06   19:06   null   null   null
  117, 4, Monday,   9:09, 9:39, 10:59, 12:09, 14:09  18:09   19:09   null   null   null
  .
  .
  .
  117, 20, Monday,   9:39, 10.09, 11:39, 12:39, 14:39  18:39   19:39   null   null   null
  119, 1, Monday,   9:00, 9:30, 10:50, 12:00, 14:00  18:00   19:00   20:00  21:00  22:00
  119, 2, Monday,   9:03, 9:33, 10:53, 12:03, 14:03  18:03   19:03   20:03  21:03  22:03
  119, 3, Monday,   9:06, 9:36, 10:56, 12:06, 14:06  18:06   19:06   20:06  21:06  22:06
  119, 4, Monday,   9:09, 9:39, 10:59, 12:09, 14:09  18:09   19:09   20:09  21:09  22:09
  .
  .
  .
  119, 37, Monday,   9:49, 9:59, 11:59, 12:59, 14:59  18:59   19:59   20:59  21:59  22:59
  139, 1, Sunday,   9:00, 9:30,  20:00  21:00  22:00  null   null     null    null   null  
  139, 2, Sunday,   9:03, 9:33,  20:03  21:03  22:03  null   null     null    null   null  
  139, 3, Sunday,   9:06, 9:36,  20:06  21:06  22:06  null   null     null    null   null  
  139, 4, Sunday,   9:09, 9:39,  20:09  21:09  22:09  null   null     null    null   null  
  .
  .
  .
  139, 20, Sunday,   9:49, 9:59, 20:59  21:59  22:59  null   null     null    null   null  
  </code></pre>