Return a default value if no rows found

Question

I have the following select statement, to grab the next scheduled item for a stream. If there is no matching row, I want it to return a default value. Here\'s the line I\'m

Answer 1

One way to do it

SELECT IFNULL(MIN(`file`), 'default.webm') `file` 
  FROM `show`, `schedule` 
 WHERE `channel` = 1 AND `start_time` <= UNIX_TIMESTAMP() 
   AND `start_time` > UNIX_TIMESTAMP()-1800 AND `show`.`id` = `schedule`.`file` 
 ORDER BY `start_time` DESC LIMIT 1

Since you return only one row, you can use an aggregate function, in that case MIN(), that ensures that you'll get NULL if no records selected. Then IFNULL() or COALESCE() will do its job.