If I learn SQL, will I be able to use any of the implementations that use SQL?
Yes, you will be able to communicate with a database whose implementation is ANSI SQL-compliant. If an implementation is not completely compliant, you should be able to pick it up quickly with some adjustments.
In a client/server environment, is the personal computer the client or the server?
The personal computer is known as the client, although a server can also serve as a client.
Do I have to use _TBL for each table I create?
Certainly not. The use of _TBL is a standard chosen for use to name and easily identify the tables in your database. You could spell out TBL as TABLE, or may want to avoid using a suffix. For example, EMPLOYEE TBL could simply be EMPLOYEE.
What happens when I am inserting a new record into a table and am missing, for example, a new employee's phone number, and the column for the phone number entry is NOT NULL?
One of two things will happen. Because the column was specified as NOT NULL (something must be entered), and because you do not have the necessary information, you could delay inserting the record until you have the phone number. Another option is to change the column from NOT NULL to NULL, thereby allowing you to update the phone number later when the information is received. One other option would be to insert a default fake value, such as 1111111111, and then change it later after receiving the correct information. Changing the column definitions is discussed in Hour 3.