SQL Found the previous date from another row matching query looking for a little more data now and a 'replace'?

Question

So m.zam worked out the answer. Thank you very much. Can anyone take this a little bit further? Here's the two tables. There are two things I'm trying to do now, replace a returned null date with the words 'New Song' and I'm trying to find out how many shows have there been since a song was last played.

song_id   song_name
  51  |  Song Name A
  368 |  Song Name B
  168 |  Song Name C
  568 |  Song Name D
  13  |  Song Name E


song_id | song_order|        show_date      |show_id
368     |     1     |  2010-02-17 00:00:00  |  367      
368     |     0     |  2012-04-06 00:00:00  |  499 
51      |     2     |  2012-01-19 00:00:00  |  399
51      |     2     |  2013-04-24 00:00:00  |  870 
51      |     8     |  2013-07-19 00:00:00  |  899 
368     |     2     |  2013-07-19 00:00:00  |  899 
13      |     5     |  2013-07-19 00:00:00  |  899 
568     |     2     |  2013-07-19 00:00:00  |  899
368     |     4     |  2012-06-08 00:00:00  |  799 
168     |     2     |  2013-06-28 00:00:00  |  896 
568     |     2     |  2013-07-03 00:00:00  |  897 
568     |     2     |  2010-02-21 00:00:00  |  897 

My code below is working to return this but I need some more data. I'm looking to turn the first table into the second. Thanks in advanced! Code can be found here: http://sqlfiddle.com/#!2/f3e29/1

FIRST

  SHOW_DATE    | SHOW_ID |   SONG_NAME | SONG_ID |     PREVDATE    |
July, 19 2013  |     899 | Song Name A |      51 | April, 24 2013  |
July, 19 2013  |     899 | Song Name B |     368 | June, 08 2012   |
July, 19 2013  |     899 | Song Name E |      13 | (null)          |
July, 19 2013  |     899 | Song Name D |     568 | July, 03 2013   |

SECOND

  SHOW_DATE    | SHOW_ID |   SONG_NAME | SONG_ID |     PREVDATE    |  SHOWS SINCE
July, 19 2013  |     899 | Song Name A |      51 | April, 24 2013  |       2
July, 19 2013  |     899 | Song Name B |     368 | June, 08 2012   |       4
July, 19 2013  |     899 | Song Name E |      13 | NEW SONG        |       0
July, 19 2013  |     899 | Song Name D |     568 | July, 03 2013   |       0



   SELECT a.show_date, a.show_id, 
    b.song_name, a.song_id, (
    SELECT
      IFNULL(MAX(show_date),'NEW SONG')
    FROM tbl_shows AS c
   WHERE a.show_date > c.show_date and a.song_id = c.song_id
   ) As PrevDate
   FROM tbl_shows a, tbl_songs b
   WHERE a.song_id = b.song_id
   AND a.show_id = 899

Though IFNULL works in SQL, im using PHP to change the format of the returned date to something more like mm/dd/yy, could I change the date in SQL before sending it to PHP or write a IF ELSE statement in the PHP to return either mm/dd/yy or 'NEW SONG'

  echo "<td style='padding: 10px; width:45px;'>" .date("m/d/y",   
   strtotime($row["PrevDate"]))." </td>";

Answer 1

Try this for the first part (NEW SONG)

 SELECT a.show_date, a.show_id, 
  b.song_name, a.song_id, 
 (
  SELECT IFNULL(MAX(show_date),'NEW SONG')
  FROM tbl_shows AS c
  WHERE a.show_date > c.show_date and a.song_id = c.song_id
  ) As PrevDate
  FROM tbl_shows a, tbl_songs b
  WHERE a.song_id = b.song_id
  AND a.show_id = 899