What are common issues when converting German date formats to MySQL date formats in PHP functions?

When converting German date formats to MySQL date formats in PHP functions, a common issue is the difference in date formats between the two systems. To solve this, you can use the `DateTime` class in PHP to parse the German date string and then format it into the MySQL date format.

// German date format
$germanDate = '31.12.2022';

// Parse German date and format it into MySQL date format
$date = DateTime::createFromFormat('d.m.Y', $germanDate);
$mysqlDate = $date->format('Y-m-d');

echo $mysqlDate; // Output: 2022-12-31