This source code covers a lot of Extjs 4 especially MVC architecture, Stores, Models and Controllers. I highly recommend that you read and attempt to do this tutorial (http://docs.sencha.com/ext-js/4-0/#!/guide/application_architecture) before getting started with the php and mysql.
Here are the instructions:
- Unzip CRUD_Extjs4.zip to your web environment
2)Create Mysql Database: CRUD_Extjs4
3)Execute the sql file: CRUD_Extjs4.sql in the database.
4)Run CRUD_Extjs4 on your server. :)