Question

I have a table that contains the next columns:

ip(varchar 255), index(bigint 20), time(timestamp)

each time something is inserted there, the time column gets current timestamp.
I want to run a query that returns all the rows that have been added in the last 24 hours.
This is what I try to execute:

SELECT ip, index FROM users WHERE ip = 'some ip' AND TIMESTAMPDIFF(HOURS,time,NOW()) < 24

And it doesn’t work.

Answer 1

HOURS should be HOUR. See the documentantion for TIMESTAMPADD to see the valid values of the unit parameter:

TIMESTAMPADD(unit,interval,datetime_expr)

Adds the integer expression interval to the date or datetime expression datetime_expr. The unit for interval is given by the unit argument, which should be one of the following values: FRAC_SECOND (microseconds), SECOND, MINUTE, HOUR, DAY, WEEK, MONTH, QUARTER, or YEAR.

So your query should be:

SELECT ip, index
FROM   users
WHERE  ip = 'some ip'
AND    TIMESTAMPDIFF(HOUR, time, NOW()) < 24

Note also that this query won’t be able to take advantage of an index on time, if one exists. It could be more efficient to rewrite the query as follows:

SELECT ip, index
FROM   users
WHERE  ip = 'some ip'
AND    time > NOW() - interval 1 day