SQL (Structured Query Language) predates Microsoft.  It is the language
used to write database searches/queries in most modern commercial database
systems.  It's virtually impossible to buy an off-the-shelf database
package that doesn't use some form of SQL these days.  So, as the original
poster wrote, if you're working with library databases, you'll probably be
working with SQL or some commercial variant of SQL.  SQL supports Boolean
logic, truncation, wildcards, if-then statements, and more.

Note that database searchers aren't aware they are using SQL.  Raw SQL
reads like most programming languages - gibberish to the average person.
Database designers create (hopefully) user-friendly front-ends that turn
user input into SQL when searches are processed.

The original poster also asked about the use of databases in web pages.
Web pages are made "dynamic" through the use of a database as a back-end.
This includes allowing entire database searches, as in PubMed or Yahoo.  It
also includes updating parts of web pages via database searches.

For example, we use mSQL (mini-SQL) in conjunction with PHP (Personal Home
Page) to publish databases on the NN/LM web site.  These both have the
advantage of being free, though not as easy to design with as some
commercial systems.  You can search some of our databases/directories.  In
addition, some of our web pages include built-in database queries (in mSQL)
that automatically generate the information when you request the page.
When you look at a page of information about Illinois, the addresses of
Resource Libraries in Illinois are pulled out of the database each time the
page is accessed.  Note that users of our web site can't even tell this
happens, as the search results are sent to the browser - not the search
query.  The advantages are obvious.  When we update an address in our
database in our office, the web site is automatically updated everywhere
that address appears - and we don't have to find and update every instance
of the address.

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I'm going to be dead for billions and billions of years.  If I don't make a
fool of myself on a regular basis, I'll feel like I've wasted my life.
Chris Shaffer  [log in to unmask]  http://www.uic.edu/~shaffer/