You can type each SQL Command at the SQL> prompt and end it with a semiconlon - ; This Works fine. You might however, choose to write your commands and execute them altogether, by running a script.
1. Using the tect editor of your choice(e.g., Notepad, TexPad, WordPad), create a file called myCommands.sql. The .sql qualifier is not required, but is highly recomended.
2. Scripts can contain commnets. the convention for writing comments is: /* Your comments here, not sql Commands */. You should comment all you scripts. Imagine you want to figure out what you did 6 months down the road!!! you will be thankful you took the time to write comments.