occur after the database design is complete. The following paragraphs discuss these stages in detail.
Fourth Stage - Implementation
During the implementation stage of the DBLC, the tables developed in the ER diagram (and subsequently normalized) are converted into SQL statements. These SQL statements are then executed in the RDBMS to create a database.
By this stage in the database life cycle, the System Administrator has installed and configured an RDBMS.
In this case the System administrator is the person responsible for administering a multi-user computer system. His duties range from setting up and configuring system components (i.e. an RDBMS) to performing maintenance procedures (for example, database backups) on the system.
Certain database design books consider converting an ER diagram into SQL statements to be the final task in the logical-design stage. According to such books, implementation is just a matter of feeding SQL statements into an RDBMS and populating the database with data. The difference is not especially important.
Fifth Stage - Monitoring, modification, and maintenance
A successfully implemented database must be carefully monitored to ensure that it is functioning properly and that it is secure from unauthorized access.
The RDBMS usually provides utilities to help monitor database functionality and security.
Database modification involves adding and deleting records, importing data from other systems (as needed), and creating additional tables, user views, and other objects and tools.
As an organization grows, its information system must grow to remain useful.
A well-designed database enhances the organization's ability to expand its information system.
Ongoing maintenance procedures include periodic database backups, for example, an important and ongoing maintenance procedure.
Again, the RDBMS provides utilities to assist in this task. The next lesson introduces a special class of tools often used in database design.
information system: Interrelated components (i.e., people, hardware, software, databases, telecommunications, policies, and procedures) that input, process, output, and store data to provide an organization with useful information.