It looks like you are encountering an error with the message "SQLSTATE[42S22]: Column not found: 1054 Unknown column".
This error message typically indicates that the MySQL server is unable to authenticate the user 'root'@'localhost' with the provided password.
It is true that the MySQL extension is deprecated, and it is recommended to use either MySQLi or PDO instead.
You can use environment variables in your application.properties file by using the spring.profiles.active property.
UTF-8 is a character encoding that represents each character in a text document as a unique numerical code.
This error message is indicating that there is a problem connecting to the MySQL server.
The mysql_* functions in PHP are deprecated, meaning that they are no longer recommended for use and will likely be removed in a future version of PHP.