Get date, explode, use data to select options in <select>

I have three variables set, $date_legible (in the format of F jS, Y, i.e. January 1st, 2011), $date_timestamp (self-explanatory), and $date_normal (in the format of YYYY-MM-DD)

I have three select fields:

    <select name="date_mo">
        <option value="01">January</option>
        <option value="02">February</option>
        <option value="03">March</option>
        <option value="04">April</option>
        <option value="05">May</option>
        <option value="06">June</option>
        <option value="07">July</option>
        <option value="08">August</option>
        <option value="09">September</option>
        <option value="10">October</option>
        <option value="11">November</option>
        <option value="12">December</option>
    </select>
    <select name="date_dy">
        <option value="01">1</option>
        <option value="02">2</option>
        <option value="03">3</option>
        <option value="04">4</option>
        <option value="05">5</option>
        <option value="06">6</option>
        <option value="07">7</option>
        <option value="08">8</option>
        <option value="09">9</option>
        <option value="10">10</option>
        <option value="11">11</option>
        <option value="12">12</option>
        <option value="13">13</option>
        <option value="14">14</option>
        <option value="15">15</option>
        <option value="16">16</option>
        <option value="17">17</option>
        <option value="18">18</option>
        <option value="19">19</option>
        <option value="20">20</option>
        <option value="21">21</option>
        <option value="22">22</option>
        <option value="23">23</option>
        <option value="24">24</option>
        <option value="25">25</option>
        <option value="26">26</option>
        <option value="27">27</option>
        <option value="28">28</option>
        <option value="29">29</option>
        <option value="30">30</option>
        <option value="31">31</o开发者_JAVA百科ption>
    </select>
    <select name="date_yr">
        <?php for($year=$curryear;$year<$curryear+51;$year++){ ?>
            <option value="<?php echo $year; ?>"><?php echo $year; ?></option>
        <?php } ?>
    </select>

I know I want to convert the timestamp, but I will ultimately need to explode the output for the $month, $day, and $year. The problem is I don't know how to check the selects to the values and automatically select the correct option.

Can anyone help? Thanks!

UPDATE

I now have one more variable, because I'm having users submit from the front end, and Gravity Forms submits as YYYY-MM-DD.

Prior to diving into the solutions already posted (thank you guys [and gals] by the way), here's a little more information:

I'm running WordPress and have three custom fields as described above. When a user submits a post from the front end, the only custom field that's filled out is $date_normal. This is okay, because a post has to be moderated (i.e. published) from the backend. What I NOW need is on load to set the YYYY-MM-DD to set the options on the select. I'm not asking you guys to alter your answers, I'm sure I can figure it out (though if you can help with this new problem, it would be greatly appreciated).

If I understand your question correctly, you have a timestamp and you need to use the timestamp to select the appropriate select options when you render the page.

As a forewarning - this will make it possible to select invalid dates, for example February 31st (does not exist). You may want to consider re-drawing the year drop-down when the month is changed using javascript. Since you didn't specify any javascript library (and it is not clear how important the possibility of an invalid date is), I will not venture to show code for that, but it would not be terribly difficult.

// using the current time for the sake of the example, your timestamp would take the place of this
$timestamp = time();

// determine the selected month, day, and year
$selected_month = date('n', $timestamp);
$selected_day = date('j', $timestamp);
$selected_year = date('Y', $timestamp);

// now, create the drop-down for months
$month_html = '<select name="date_mo">';
for ($x = 1; $x < 13; $x++) {
    $month_html .= '<option value='.$x.($selected_month == $x ? ' selected=true' : '' ).'>'.date("F", mktime(0, 0, 0, $x, 1, $selected_year)).'</option>';
}
$month_html .= '</select>';
// output
print $month_html;


// create the day drop-down
$day_html = '<select name="date_day">';
for ($x = 1; $x < 32; $x++) {
    $day_html .= '<option value='.$x.($selected_day == $x ? ' selected=true' : '' ).'>'.$x.'</option>';
}   
$day_html .= '</select>';
// output
print $day_html;


// create the year drop-down
$year_html = '<select name="date_year">';
$start_year = date('Y', time());
$max_year = $start_year + 51;
for ($x = $start_year; $x < $max_year; $x++) {
    $year_html .= '<option value='.$x.($selected_year == $x ? ' selected=true' : '' ).'>'.$x.'</option>';
}   
$year_html .= '</select>';
// output
print $year_html;

Output:

EDIT If your source data will be in the format of YYYY-MM-DD. In order to translate that into a timestamp, and thus work with the example code I've posted, is to call strtotime on that formatted date value. Thus, the only line in the code above that would need to be changed is $timestamp = strtotime($the_formatted_date);

<?php
    // $months = array(1 => 'January', 2 => 'February', ... etc
?>
<select name="date_mo">
<? for ($i = 1, $current = (int) date('n'); $i <= 12; $i++) { ?>
    <option value="<?=$i;?>"<?=($current === $i ? ' selected="selected"' : NULL);?>><?=$months[$i];?></option>
<? } ?>
</select>
<select name="date_dy">
<? for ($i = 1, $current = (int) date('j'); $i <= 31; $i++) { ?>
    <option value="<?=$i;?>"<?=($current === $i ? ' selected="selected"' : NULL);?>><?=$i;?></option>
<? } ?>
<select name="date_yr">
<? for ($i = $current = (int) date('Y'), $until = $i + 50; $i <= $until; $i++) { ?>
    <option value="<?=$i;?>"<?=($current === $i ? ' selected="selected"' : NULL);?>><?=$i;?></option>
<? } ?>
</select>

I would personally convert the 3 fields to a more user-friendly date selector (using for example jQuery UI), but to have the correct option selected when you open the page, you need to add a check to each option.

Example for the year:

  <?php
      $selected_year = date("Y", $date_timestamp);      // get the selected year
      for($year=$curryear;$year<$curryear+51;$year++)
      {
  ?>
        <option value="<?php echo $year; ?>" <?php echo ($selected_year == $year) ? 'selected' : ''; ?>><?php echo $year; ?></option>
  <?php
      }
  ?>