php怎么表示从当前日期起三个月之内的数据

php如何表示从当前日期起三个月之内的数据
php如何表示从当前日期起三个月之内的数据
查询语句用那个函数？
------解决方案--------------------

echo $deltime=strtotime("-90 days");

echo "

---

";
$sql="delete from yourtable where dateandtime<".$deltime;
echo $sql;echo "

---

";
$con = mysql_connect("localhost","root","yourpassowrd");
if (!$con)
{
die('Could not connect: ' . mysql_error());
}
mysql_select_db("yourdb", $con);
mysql_query($sql,$con);
mysql_close($con);

echo "

---

Are You OK?

---

";
echo time();
?>