Standardization

Earlier, we mentioned that SQL was the industry standard for relational databases. Computer standards are adopted, coordinated, and maintained by the American National Standards Institute (ANSI), a privately run and not-for-profit organization. You can learn more about this organization at www.ansi.org. The International Organization for Standardization (ISO) and the U.S. government have also adopted SQL as the standard support language for relational database systems.

What standardization means is that software producers and developers have a universally agreed upon set of statements and syntax rules that they can quickly learn and apply to their own work. In a nutshell, if you know SQL, you can quickly learn how to communicate with almost any relational database.

ANSI published the first SQL standard in 1986. To date, the standard has been updated twice, in 1992 and again in 1998. Electronic copies of the 1992 and 1998 versions of these standards are available at http://webstore.ansi.org for $18.00 each. When searching for the standards, refer to the document number X3-135. If you prefer, you can purchase hard copies from American National Standards Institute, 1819 L Street, NW, Suite 600, Washington, DC 20036. Hard copies are, as a rule, expensive.

Vendor Dialects

Despite standardization, many dialects of SQL exist. That's because software vendors expound on the standards by adding numerous customized features known as vendor-specific extensions to their proprietary versions. Consequently, every RDBMS that supports SQL offers its own brand, or dialect, of SQL. Generally, these extensions are available only through specialized code, which, of course, is specific and unique to the system. Standard SQL may be all you ever need, but make an effort to learn the system's extensions. Often, these extensions include specialized options and features that you might otherwise have to create on your own.