The programmers of oracle database normally used the sqlplus to write and execute commands like;
SQL > select * from tab;
To display fileno, name, we have to write the command;
SQL > select file_no,name from emp;
If we have to add another column, we have to write the whole command again;
SQL > select file_no,name,sal from emp;
In sql plus, it is not possible to change/edit the previous commands easily. We have to write the whole command completely or we use the note pad to edit the commands.
I have recently installed another software ''sql pal editor''. It is small size software. It is better and the previous command can be edit/changed with up or down arrow keys. So you do not have to write the command again.
So you run the sqlpal editor and first of all you connect to the username and password.
Now you are connected to sql pal.
SQL> select file_no, name from emp;
The output will be display in the lower.
Now you want to add another column 'sal' in the above command. so you only press upward arrow key. The above command will be display no you add column as:
SQL>select file_no, name, sal from emp;
Press Enter. The output of three column will be displayed.