You will need this for Skype, for example. If you try to install the current version
on a newish 64-bit Debian machine, it will complain about a bunch of missing dependencies. What you need to do:
dpkg --add-architecture i386
dpkg -i /path/to/skype-debian_18.104.22.168-1_i386.deb
apt-get -f install
after which a whole pile of *:i386 32-bit packages should install on your 64-bit machine. And skype should start now. But, you may find your sound does not work, as there seems to be a missing dependency. This
apt-get install libpulse0:i386
fixed it for me. Further note that you may have to add
deb http://www.deb-multimedia.org main
to your /etc/apt/sources.list to find some dependencies that are sometimes not available in vanilla Debian.
Assuming you have an Oracle database running and need to do "stuff" with it, sqlplus is probably the tool (DB client) you are looking for. There are some instructions out there for installing an sqlplus client on your Debian desktop, but (so far) I have found making remote connections to an Oracle database to be problematic. It is easiest to run sqlplus on the Oracle machine itself, where sqlplus will always be a part of the install, and configuration is much easier.
First set up some environment variables required by sqlplus by adding the following to /home/oracle/.bashrc:
These settings are obviously environment-dependent. I believe that orcl is the default name for an Oracle database in a default installation, but per you can find the name(s) of Oracle database(s) configured in /etc/oratab.
./sqlplus "/as sysdba"
If your background is MySQL, for instance, things now start getting funky. An Oracle "database" is more akin to a MySQL instance. An Oracle "schema" within that "database" is the equivalent, it seems, of a MySQL database. And there is no straight-forward way to get a list of schemas. Apparently in Oracle there is a one-to-one relationship between Oracle username and schema. So a list of users is a superset of the list of schemas (since not all users have a schema). These
SQL> SELECT username FROM dba_users WHERE default_tablespace not in ('SYSTEM','SYSAUX');
SQL> select distinct owner from dba_objects;
for instance get you an approximation of such a list of schemas, but produce slightly different results. And this
SQL> SELECT DISTINCT OWNER, OBJECT_NAME FROM DBA_OBJECTS WHERE OBJECT_TYPE = 'TABLE' AND OWNER = '[some other schema]';
(godawful!!) query will then show you the list of tables associated with a schema (OWNER parameter above). And
SQL> describe schema.tablename
then describes the columns of a table.