Question

I have an array from this mysql query:

SELECT COUNT(*) as opens, HOUR(FROM_UNIXTIME(open_date)) as hour 
FROM tracking WHERE open_id = 10 GROUP BY HOUR(FROM_UNIXTIME(open_date)) 

It allows me to get opens based on every hour. However, there are some gaps in the hours as nothing has been opened at a particular hour. How can I fill the gaps i.e. turn this array:

Array ( 
[0] => Array ( [opens] => 9 [hour] => 0 ) 
[1] => Array ( [opens] => 2 [hour] => 3 ) )

Into:

Array ( 
[0] => Array ( [opens] => 9 [hour] => 0 ) 
[1] => Array ( [opens] => 0 [hour] => 1 ) 
[2] => Array ( [opens] => 0 [hour] => 2 ) 
[3] => Array ( [opens] => 2 [hour] => 3 ) )

In other words fill missing hours with 0 opens? Can I change my sql query to get this to work or will it have to be via PHP?

Thanks all for any help.

Answer 1

You could do it in code based on the results that you get back. One way to do it using only the database would be to have a table (maybe even a temporary one) that contains the hours and do a left outer join on hours vs. tracking. Note that this is practical only because the range for hours is fixed and relatively small — basically a single column containing the numbers 0-23.

SELECT COUNT(*) as opens, hours.hour
FROM hours
LEFT OUTER JOIN tracking ON hours.hour = HOUR(FROM_UNIXTIME(tracking.open_date))
WHERE tracking.open_id = 10
GROUP BY hours.hour