如何检查输入日期是否在过去90天内在PHP中

I am using jquery date picker and from that i got the date as a format of yyyy-mm-dd. what i need to know that, i want to check the input date is in last 90 days or not from today.

$( "#dt_affected" ).datepicker({
        changeMonth: true,
        changeYear: true,
});

and i read it in php as $posted["dt_affected"]= $this->input->post("dt_affected", true); and i got the result 2011-06-15 thanks in advance

If you want to check date on server side the you can use the following code

echo date ( $format, strtotime ( '-90 day' . $date ) );