When we work with object-oriented system, will encounter incompatibility issues between the type of object and relational databases. The management system database relations (RDBMSs) shows data in tabular format, whereas the language object-oriented programming such as Java, C #, C ++ representation of data in graphs link Subjects. ORM is the solution to solve the problem of incompatibility hinders on.

PHP is a programming language used to build applications Website, or in other words it is the main language used for programming the server to handle the requirements of the client. And MySQL is a database management system for storing data and it is often used together with PHP since he was born, this is a perfect couple used to build websites.

Most users at one time or another have dealt with hierarchical data in a SQL database and no doubt learned that the management of hierarchical data is not what a relational database is intended for. The tables of a relational database are not hierarchical (like XML), but are simply a flat list. Hierarchical data has a parent-child relationship that is not naturally represented in a relational database table.