So far throughout this book, we've made a number of connections to our Oracle database using both SQL Developer and SQL*Plus, but we've yet to really discuss the details of what happens during these connections. Let's examine a simple connection that we've already used.
We make a connection to the database using SQL*Plus by providing a username and password, as we mentioned in our chapter on database security. This type of connection is known as a
local connection—no remote database is specified. Thus, when no connection information other than a username and password are specified, an assumption is made that the connection is local, and it is determined only by the value for the ORACLE_SID environment variable. Rather than using a network protocol, such as TCP/IP, local connections use the Inter-Process Communication
(IPC) protocol. Thus, our SQL*Plus can use IPC, since our client SQL*Plus session is on the same machine as our database. This is only true if we...