Database Reference
In-Depth Information
Next, the database must be created and configured. Depending on the DBMS
suite that is in use, database creation and configuration may be very simple or quite
complicated. In some systems (for example Delphi), database creation is a simple act of
creating a directory (in the Linux environment) or folder (in the Windows environment),
and then creating database aliases that point to that directory or folder. In others such as
MySQL, there is a highly simplified
Create-Database
statement that allows you to create
a database within seconds. On the other end of the spectrum, there are systems such as
Oracle, for which you must first complete a course before you know how to properly create
a database (review Oracle's version of the
Create-Database
statement in Chapter 11).
And there are those products in between the two extremes.
Once you have created the database, there are issues that must be determined as
part of the database configuration. These issues include the following:
•
Location of the database and its related files
•
Communication issues for server and client (for client-server
databases) in a multi-user environment
•
Physical structure of the database
•
Logical structure of the database
•
Users of the database and their access rights
Like database creation, the complexity of these issues, and the flexibility with which
they can be addressed, will depend to a large extent on the products involved, as well as
the complexity of the database itself.
21.2 Database Security
Database security is a very important aspect of database administration. Ideally, the
security mechanism must be multi-tiered, controlling access to the system, the system
resources, and the system data. The DBA must ensure the following:
•
Access to the system is controlled.
•
Authorized users must be able to access (insert, modify, retrieve
or delete) data that they are authorized to access.
•
Authorized users must be restricted to the data and resources that
they are duly authorized to access and nothing more.
•
Unauthorized users must have absolutely no access.
In order to achieve this, the DBA must be fully conversant with SQL facilities
(commands) for managing database users and objects. The information covered in
Chapter 13 is particularly relevant here. Some DBMS suites are marketed with a GUI,
which is superimposed on the basic SQL interface, and provides a more user-friendly
environment for working, by generating SQL code (which can be subsequently accessed
and modified) to GUI-based instructions. Examples of this in the Oracle suite include
Oracle Enterprise Manager (OEM), iSQL Plus, and Oracle SQL Developer (OSQLD).
