How to use SQLPlus to connect to oracle and use it in unix scripts? Connect strings

How to use SQLPlus to connect to oracle and use it in unix scripts? SQL Plus Connect strings and commands :

Sqlplus is a command line tool that comes with any oracle client that can be used to connect to oracle database. It can also be used in scripts to send commands to oracle database.

The common sqlplus connection string is:

sqlplus username/password@servername:port/databasename 

Go to the directory where sqlplus is location and enter the above command with proper username, password supplied to the command as shown in the connection string.

To find list of tables in the database use the command in sqlplus:

select table_name from user_tables;
 
Rest of the DML and DDL statements from oracle work in SQL plus.

If you want to use sqlplus in an unix script then the below sample unix script should help:

#/usr/bin/ksh
sqlplus username/password@servername:port/databasename << EOF
WHENEVER SQLERROR EXIT 2;
insert into mytable select * from mytemptable;
EOF
RTN=$?
if [ $RTH -ne 0] ; then
echo failed