What are common issues when configuring PHP extensions like php_mysql.dll in Apache?

Common issues when configuring PHP extensions like php_mysql.dll in Apache include incorrect extension directory paths in php.ini, missing dependencies, or conflicts with other extensions. To solve this, ensure that the extension directory path in php.ini is correctly set to the folder containing the php_mysql.dll file, check for any missing dependencies or conflicts with other extensions, and restart Apache after making any changes.

extension_dir = "C:/path/to/php/ext"
extension=php_mysql.dll