Unix Timestamp to Mysql time stamp

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I need to change the format of a unix time stamp to the correct format for a mysql time stamp

How can i do this?

this is what i have getting the unix timestamp so far now i just
have to get it converted into a mysql timestamp

$overdue_time = time(Y,m,d) + (86400 * $lst_period);
$enter_time = $overdue_time - (86400 * $lst_period);