Database Connection

• To connect to your database, you have to create a handle: this handle actually links the interface classes with the 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.

• Once your handle is created, you have to create a session manager which will allow you to manage your database; specifically, to establish a connection, disconnect and also handle errors. The class DB_CONTROL enables your application to 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