Store year as a date field without day or month

[s2e]

I am collecting the date in a form with individual month, day, year fields and then forming a string (YYYY/MM/DD) to submit to MySQL. It is very common for a user to know an appropriate year to enter, but unable to enter the day and/or month. In this circumstance the year value when submitted is lost because the 2006/00/00 is an invalid date. Is it possible to save the year in DB (datatype=date) without using separate new field? I really dont want to display a default month/day either. Any ideas? Here's my code:

$form = 'Y';
if(isset($_POST['continue'])) {

$message = NULL;

if(empty($_POST['f_name'])) {
	$f_name = FALSE;
	$message .= '<p>Please enter a First Name.</p>';
	} else {
	$f_name = $_POST['f_name'];
}

if(empty($_POST['l_name'])) {
	$l_name = FALSE;
	$message .= '<p>Please enter a Last Name.</p>';
	} else {
	$l_name = $_POST['l_name'];
}

if(empty($_POST['d_name'])) {
	$d_name = FALSE;
	$message .= '<p>Please enter a Display Name.</p>';
	} else {
	$d_name = $_POST['d_name'];
}

$birth_date = "{$_POST['birth_year']}/{$_POST['birth_month']}/{$_POST['birth_day']}"; //FORMATTING THE DATE
$death_date = "{$_POST['death_year']}/{$_POST['death_month']}/{$_POST['death_day']}"; //FORMATTING THE DATE
$home_city = $_POST['home_city'];
$home_state = $_POST['home_state'];

$creator_id = $_SESSION['fun_id'];

if ($f_name && $l_name && d_name) {
	require_once ('x/mysql_connect.php');
	$query = "INSERT INTO obituary (
	creator_id, 
	creator_type, 
	created, 
	first_name, 
	last_name, 
	display_name, 
	birth_date,
	death_date, 
	home_city, 
	home_state) 
	VALUES (
	'$creator_id', 
	'A', 
	NOW(), 
	'$f_name', 
	'$l_name', 
	'$d_name', 
	'$birth_date',
	'$death_date', 
	'$home_city', 
	'$home_state')";
	$result = @mysql_query($query);
	if ($result) {
		$query1 = "SELECT obit_id FROM obituary ORDER BY obit_id DESC LIMIT 1";
		$result1 = @mysql_query($query1);
		$row1 = mysql_fetch_array($result1, MYSQL_NUM);
		$obit_id = $row1[0];
		$form = 'N';

	} else {
	echo mysql_error();
	} 
}
}

[bpat1434]

I see a couple options here:

1.) Separate fields in the database that are integers, one for the year, day and month. Then you CONCAT() the field values into your date format, and perform the functions on that CONCATenated value.

2.) Default date. You could use any arbitrary date you want, just as long as you know it's default. Something like 1/2/200X or something... although you have the issue of someone acutally having something on that date, and you showing it as unknown.

3.) Flagging. You set a flag in the database. You use a default value. If the flag is set, you know they didn't submit a day/month and what's in there should only be the year. If it's not set, use the entire date. This flag could be three fold: Y or M or D. if it's Y then only the year, if it's M then only the month, if it's D then only the D is the valid option. Of course you could use YM, YD, DM as needed.

Those are three options, but how you implement is up to you.

[s2e]

Thanks bpat. I think im just goin to store Y M D in seperate fields and then have one full date field that may or may not be complete. Thing is that I am displaying the date throughout several parts of the site, to CONCAT the indiv fields for display is easy enough, but I also have some search functions that need a true date field because I am working with ranges etc. Really dont want to use a default date for incomplete entries for several reasons, so #1 seems to be my best option. Thanks for the input.