How can I find the age of a record in minutes when using MySQL?

I have a history table with a datetime field named createdAt. I'm trying to determine the age of the record but the age column comes back as Null:

SELECT id, (MINUTE(TIMEDIFF(NOW(),IFNULL(history.createdAt,0)))) AS age
FROM history
WHERE history.type = @type

I tried DATEDIFF() instead of TIMEDIFF() and I get a 0 back

Any idea why this 开发者_StackOverflow社区query is not behaving as expected?

UPDATE:

After introspecting the database, I found that the createdAt column was a date and not a datetime column. The code works as expected if using a datetime column.

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Not able to test right now, but the API says:

Returns the minute for time, in the range 0 to 59.

mysql> SELECT MINUTE('2008-02-03 10:05:03');
        -> 5

http://dev.mysql.com/doc/refman/5.5/en/date-and-time-functions.html#function_minute

-- not what you want to do. Try TIME_TO_SEC() on the result from TIMEDIFF, and divide it by 60 to get minutes.