I've only learned Java last quarter of 2010. I can say the knowledge I gained as of now are not enough and there's a lot of improvement. I still do studying while developing but most of my code is snippet from other current working application. I guess my way of studying the language affect the way I know it. Instead of learning the basic first, I jump up to advanced features that affect how I understand it. (I did advanced to fulfill my previous project tasks.)

I often connect to my MySql database using `import java.sql.connection` etc. I'm using Eclipse IDE then when I create an instance of Connection/PreparedStatement and I haven't imported the packages. Eclipse will show related Packages that's where `mysql.jdbc.*` I've encountered. 

All though I did some research about it still its not too clear for me. The difference of those to packages. 

* Does it have pros and cons?
* Does it have a big significance difference with performance and security?
* Does it use in different way?
* Is there more things to know?

I know someone here can enlighten me more about this.