SQL*Plus is a tool used to enter SQL commands and display the output.
To start SQL*Plus, simply type 'sqlplus' at the command prompt or after starting a DOS command session in Windows.
You can leave SQL*Plus with the commands EXIT or QUIT.
A Basic SQL SELECT Command
select * from emp;
SQL commands are often spread over multiple lines and SQL*Plus automatically displays line numbers.
If your SQL command is fully entered and to execute, finish the last line with a semicolon ; as a delimiter.
You can enter that semicolon on the next empty line:
select * from emp ;