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EiffelStudio

# Database Connection

1. To connect to your database, you have to create a handle: this handle actually links the interface classes with corresponding implementation classes mapped to your DBMS. This handle is implemented by the DATABASE_APPL class:

       	database_appl: DATABASE_APPL [ODBC]
       		-- Database handle.
       	...
       	create database_appl.login (a_name, a_psswd)
       	database_appl.set_base

   Note: Calling set_base links the EiffelStore interface to this specific handle.

   Tip: You can manage handles to many databases: as an instance of DATABASE_APPL stands for a specific database handle, you only have to create one instance of DATABASE_APPL for every DBMS handle you wish to create. Do not forget to call set_base to activate appropriate handle.

   Note: The generic parameter of DATABASE_APPL specifies the actual DBMS used.

2. Once your handle is created, you have to create a session manager which will allow you to manage your database, specifically to establish connection, disconnect and also handle errors. The class DB_CONTROL enables your application to plainly control the functioning and status of your database and to request any information about it.

       	session_control: DB_CONTROL
       		-- Session control.
       	...
       	create session_control.make
       	session_control.connect

   Note: Take a look at the database control part to see how to use DB_CONTROL capabilities.

See Also
Database control and error handling
Implementation