Today we are gonna see a easy way to maintain clear the tnsnames.ora

Lets see our file:

PROD=
  (DESCRIPTION=
     (ADDRESS=(PROTOCOL=tcp)(HOST=host1)(PORT=1521))
     (CONNECT_DATA=
        (SERVICE_NAME=factura)
     )
  )
PRODUCCION=
  (DESCRIPTION=
     (ADDRESS=(PROTOCOL=tcp)(HOST=host1)(PORT=1521))
     (CONNECT_DATA=
        (SERVICE_NAME=factura)
     )
  )
FACTURACION=
  (DESCRIPTION=
     (ADDRESS=(PROTOCOL=tcp)(HOST=host1)(PORT=1521))
     (CONNECT_DATA=
        (SERVICE_NAME=factura)
     )
  )

As you can see, we have three identical entries for the same database. This makes our file bigger and more difficult to maintain.
How can we solve it?
Easy, You can specify multiple net_service_name separated by command in a single entry.

This will be :

PROD,PRODUCCION,FACTURACION=
  (DESCRIPTION=
     (ADDRESS=(PROTOCOL=tcp)(HOST=host1)(PORT=1521))
     (CONNECT_DATA=
        (SERVICE_NAME=factura)
     )
  )

As you can see, easy and clear