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Calculating Time Difference


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I've seen similar solutions offered as to what I'm looking for but this is a slight twist that I need help with.


In a mySQL table, I have a "time" (not timestamp) value. Example : 18:00:00 Unfortunately I don't have have date values to show which date this time was from. Here's what I want to do.


Here's some sample data to work with:


Current Time - 14:00

Time value # 1 from a mySQL query - 18:00:00


Time value # 2 from a mySQL query - 13:00:00



In PHP, I want to assume that, any time in the future is actually from the previous day.

I then want to calculate the difference in time between the current time and any time value I pull from a query.and store that in a variable.

For example, using time value #1 from above, the difference would be 20:00:00 (since it was 20 hours ago). Using time value #2, the difference would be 1:00:00 (only 1 hour).


It sounds simple but I might be over analyzing my problem to figure this out.


Thanks for any help offered :)


- dan -

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You could do it in the query (assuming the column is defined as a TIME datatype):


SELECT IF (TIME(NOW()) < ColumnName, 
   TIMEDIFF('24:00:00', TIMEDIFF(ColumnName, TIME(NOW()))), 
   TIMEDIFF(TIME(NOW()), ColumnName)) AS `TimeDiff`
FROM TableName


There are probably half-a-dozen ways to do it in PHP, but I think doing it in the query is more efficient.

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