Hi there

How can i use SQL syntax to select a user who have lastvisit time within last 5 minutes?

I have try like this but failed
Code:
$result = mysql_query("Select * from tblmember WHERE " .( time() - 300 ) . " <= lastvisit;");

also

WHERE DATE_SUB(CURDATE(),INTERVAL -5 Minute) <= lastvisit
does anyone have an experience with something like this?
how can i do that

Thanks for advance