example.php

protected static function getFieldFlags($what)
        {
            // Order of flags taken from http://lxr.php.net/xref/PHP_5_6/ext/mysql/php_mysql.c#2507
            $constantFlagMap = [
              MYSQLI_NOT_NULL_FLAG => "not_null",
              MYSQLI_PRI_KEY_FLAG => "primary_key"
              ...
            ];
            
            $flags = [];
            
            foreach($constantFlagMap as $constant => $flag) {
              if ($what & $constant) {
                $flags[] = $flag;
              }
            }
            
            return implode(" ", $flags);
        }