how do i: SELECT all posts from the past 6 hours?

[sabret00the]

i thought it would be something simple like

PHP Code:

$lastpost = $DB_site->query_first("
    SELECT COUNT(*)
    FROM post
    WHERE dateline > 6hours
"); 


ok for the six hours i thought would i be able to just do something like

PHP Code:

$sixhours = ceil(6 * 4600);

$lastpost = $DB_site->query_first("
    SELECT COUNT(*)
    FROM post
    WHERE dateline > $sixhours
"); 


can i do that?