Mysql Compare two datetime fields

问题:

I want to compare two dates with time, I want all the results from tbl where date1 > date2

Select * From temp where mydate > '2009-06-29 04:00:44';

but it is just comparing dates not time. it is giving me all the result set of today's date

'2009-06-29 11:08:57'
'2009-06-29 11:14:35'
'2009-06-29 11:12:38'
'2009-06-29 11:37:48'
'2009-06-29 11:52:17'
'2009-06-29 12:12:50'
'2009-06-29 12:13:38'
'2009-06-29 12:19:24'
'2009-06-29 12:27:25'
'2009-06-29 12:28:49'
'2009-06-29 12:35:54'
'2009-06-29 12:36:54'
'2009-06-29 12:49:57'
'2009-06-29 12:58:04'
'2009-06-29 04:13:20'
'2009-06-29 04:56:19'
'2009-06-29 05:00:23'
'2009-06-29 05:04:26'
'2009-06-29 05:08:17'
'2009-06-29 05:26:57'
'2009-06-29 05:29:06'
'2009-06-29 05:32:11'
'2009-06-29 05:52:07'

Thanks in advance!

回答1:

The query you want to show as an example is:

SELECT * FROM temp WHERE mydate > '2009-06-29 16:00:44';

04:00:00 is 4AM, so all the results you're displaying come after that, which is correct.

If you want to show everything after 4PM, you need to use the correct (24hr) notation in your query.

To make things a bit clearer, try this:

SELECT mydate, DATE_FORMAT(mydate, '%r') FROM temp;

That will show you the date, and its 12hr time.

回答2:

You can use the following SQL to compare both date and time -

Select * From temp where mydate > STR_TO_DATE('2009-06-29 04:00:44', '%Y-%m-%d %H:%i:%s');

Attached mysql output when I used same SQL on same kind of table and field that you mentioned in the problem-

It should work perfect.

回答3:

Your query apparently returned all correct dates, even considering the time.

If you're still not happy with the results, give DATEDIFF a shot and look for negaive/positive results between the two dates.

Make sure your mydate column is a datetime type.

回答4:

Do you want to order it?

Select * From temp where mydate > '2009-06-29 04:00:44' ORDER BY mydate;