You really have day, month, and year in *SEPARATE* fields in your table???
Yes, that works for selecting a *specific* day/month/year. But it makes queries for (say) "any date from July 17, 2013, through September 3, 2013" really really really tough to do!
You should have a *SINGLE* field of type DATE!
CREATE TABLE events (
eventid INT AUTO_INCREMENT PRIMARY KEY,
...other fields ...
) ENGINE INNODB
And now, yes, you might have day/month/year as separate fields in your <form>. Perhaps thus:
<form action="seach.php" method="post">
Day: <input name="day"/> Month: <input name="month"/> Year: <input name="year"/>
Planner name: <input name="planner"/>
<input type="submit" value="Search"/>
(And, yes, any and all of those fields I showed there as <input> [only for simplicity] could be <select>s instead, of course. Won't make any difference to PHP/MySQL.)
And then your PHP code:
... make your db connection ...
$yr = $_POST["year"];
$mo = $_POST["month"];
$dy = $_POST["day"];
$name = $_POST["planner"]
if ( ! is_numeric($yr) || ! is_numeric($mo) || ! is_numeric($dy) )
echo "Year, month, and day must be numbers";
// MySQL needs dates as Y-M-D:
$dt = ((int)$yr) . "-" . ((int)$mo) . "-" . ((int)$dy);
$name = mysql_real_escape_string($name); // or use mysqli equivalent
$sql = "SELECT * FROM events WHERE eventDate = '$dt' AND plannerName='$name'";
... and make the query ...