How can PHP strings be converted to a MySQL-compatible date format?

To convert PHP strings to a MySQL-compatible date format, you can use the `strtotime()` function to convert the string into a Unix timestamp, and then use the `date()` function to format the timestamp into the desired MySQL date format. This allows you to easily convert date strings from various formats into a format that can be stored in a MySQL database.

$dateString = "2022-01-15";
$timestamp = strtotime($dateString);
$mysqlDate = date('Y-m-d', $timestamp);
echo $mysqlDate;