MySQL get the date n days ago as a timestamp

问题:

In MySQL, how would I get a timestamp from, say 30 days ago?

Something like:

select now() - 30 

The result should return a timestamp.

回答1:

DATE_SUB will do part of it depending on what you want

mysql> SELECT DATE_SUB(NOW(), INTERVAL 30 day); 2009-06-07 21:55:09  mysql> SELECT TIMESTAMP(DATE_SUB(NOW(), INTERVAL 30 day)); 2009-06-07 21:55:09  mysql> SELECT UNIX_TIMESTAMP(DATE_SUB(NOW(), INTERVAL 30 day)); 1244433347 

回答2:

I think you are after DATE_SUB.

回答3:

You could use:

SELECT unix_timestamp(now()) - unix_timestamp(maketime(_,_,_)); 

For unix timestamps or:

SELECT addtime(now(),maketime(_,_,_)); 

For the standard MySQL date format.

回答4:

If you need negative hours from timestamp

mysql>SELECT now( ) , FROM_UNIXTIME( 1364814799 ) , HOUR( TIMEDIFF( now( ) , FROM_UNIXTIME( 1364814799 ) ) ) , TIMESTAMPDIFF( HOUR , now( ) , FROM_UNIXTIME( 1364814799 ) )  2013-06-19 22:44:15     2013-04-01 14:13:19     1904    -1904 

this

TIMESTAMPDIFF( HOUR , now( ) , FROM_UNIXTIME( 1364814799 ) )  

will return negative and positive values, if you need to use x>this_timestamp

but this

HOUR( TIMEDIFF( now() , FROM_UNIXTIME( 1364814799 ) ) ) 

will return only positive, hours

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