Adding Modifying columns

1. In this simulation, you have just created a table, as seen in this screen. Your next task is to add two new columns that were forgotten. The command has been started for you. One column, HIRE_DATE, will be added. Add another column named JOB_TITLE with a datatype of VARCHAR2(20) by typing this line and pressing Enter:
   

   JOB_TITLE VARCHAR2(20) NULL);
   

2. Good. You have now added the two new columns. Another change is needed: Allow null values in the LASTNAME column. Type the following command at the SQL> prompt and press Enter:
   

   ALTER TABLE EMPLOYEE MODIFY (LASTNAME NULL);
   

3. To view the current structure of the EMPLOYEE table, type the following SQL*Plus command and press Enter:
   

   DESC EMPLOYEE
   

4. The table has two new columns: HIRE_DATE and JOB_TITLE. The LASTNAME column no longer displays the NOT NULL constraint. This is the end of the simulation. Click the Exit button.