Many CPT is conflicting of the custom date

Question

How can I fix the date with multiple Wordpress CPT date? An example, the custom post "John The Man" on "Canada" CPT the birthday is "Thursday 05 May 1960". How can I compare with only date and month (05 May) with every year (2024, 2025, etc), and skipping birthyear+time? Now it is all records/row without date, or no records/row with date. I have tried 'where' and 'meta_query' on the dates.

//index.php:

echo birthday("Canada", "dmy", "birthday", "Canada ...");
echo birthday("USA", "dmy", "birthday", "USA ...");
echo birthday("Mexico", "dmy", "birthday", "Mexico ...");
echo birthday("El Salvador", "dmy", "birthday", "El Salvador...");​
//and so on ​...

​
function birthday($custompost, $dmy, $birthday, $message) {
    $current_date = new DateTime();
    $datemonth = $current_date->format("d M");
    $args = array(
        'post_type' => $custompost,
        'post_status' => 'publish, private',
        'limit'    => '-1',

//this does not working with 'where'
        //'where' => "DATE_FORMAT(CAST(birthday.meta_value AS date), '%d %c') = '$datemonth'", //not working

//this does also not working with 'meta_query'
        'meta_query' => array(
            array(
            'key' => 'birthday', 

            'value' => $datemonth, //not working
            //'value' => '05 May', //not working
            //'value' => '%5%May%', //not working

//must remove the year+time, or else it can be only 1 birthday (e.g. Thursday 05 May 1960) for each country
            //'value' => date('Y/m/d'),
            //'value' => date('Y/m/d',time()),
​
            'type' => 'DATE', //or 'NUMERIC', not working

            //'compare' => 'LIKE', //or EXISTS, IN, could compare with from "Thursday 05 May 1960" to "05 May", skipping day and year. Not working
            )
        ) //end meta_query
    ); //end args

$posts = get_posts( $args );
echo "<pre>posts:";print_r( $posts );echo "</pre>";
echo "<pre>query:";print_r( $query );echo "</pre>";
}; //end function​
​```

Answer 1

If your posts store the date in a consistent format like YYYY-MM-DD HH:MM:SS, etc, you could compare with strings using regular expressions, like:

$current_date = new DateTime();
$datemonth = $current_date->format("m-d"); // MM-DD

$args = array(
  // …
  'meta_query' => array(
    array(
      'key'     => 'birthday',
      'compare' => 'REGEXP',
      // Regular expression explanation:
      // ^     - Start of string
      // \d    - Any digit (0-9)
      // {4}   - Four of the previous token
      // \d{4} - Four digits
      'value'   => "^\d{4}-$datemonth",