PDO4You is a class that implements the Singleton design pattern for connecting the database using the PDO extension (PHP Data Objects). It provides an abstraction layer for accessing data, regardless of which database you are using, and ensures that there is a single object instance per database connection. It can connect to several possible SQL databases using the available PDO drivers. Currently it supports MySQL, PostgreSQL, SQLite, MariaDB, Oracle, Microsoft SQL server, Sybase, and CUBRID (a database highly optimized for Web applications). The class can also execute multiple queries at once given a string in JSON format that specifies the type of query, the tables, fields, field values, conditions, etc.