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Chapter 18. Database Access with SQL
This chapter shows how you can
communicate with a database server using the JDBC API of the
java.sql package. JDBC is an API that allows a
Java program to communicate with a database server using Structured
Query Language (SQL) commands. Note that JDBC is a SQL API, not an
embedded SQL mechanism for Java.The java.sql package
provides a fairly straightforward mechanism for sending SQL queries
to a database and for receiving query results. Thus, assuming that
you already have experience working with databases and SQL, this
chapter should be relatively easy to understand. On the other hand,
if you have not worked with databases before, you'll
need to learn basic SQL syntax and some general database programming
concepts before you can really take advantage of the examples in this
chapter and JDBC in general. I'll try to explain
some of the basic concepts as I go along, so that you can get a sense
of what is possible with JDBC, but full coverage of database
programming is beyond the scope of this chapter. Java
Enterprise in a Nutshell contains a more thorough
introduction to JDBC, a SQL reference, and an API quick-reference for
the java.sql package.In order to run the
examples in this chapter, you need access to a database, and you have
to obtain and install a JDBC driver for it. If you
don't already have a database server to work with,
you can use one of the excellent open source databases available
today. The examples in this chapter have been tested with MySQL, an
open source database available from
http://www.mysql.com. PostgreSQL, another
excellent open source server, is available from
http://www.postgresql.org. JDBC drivers for
these database servers can be downloaded from the same sites. Note
that database servers are complex pieces of software. Downloading and
installing a database may require significant effort. (Installing the
driver, on the other hand, is usually easy: add it to your classpath,
or just drop it in the jre/lib/ext/ directory of
your Java installation.)Once you've decided which database server to use,
read the documentation that comes with it. Before running the
examples in this chapter, you need to know how to administer the
database server. In particular, you need to know how to create a test
database (or you need to have your database administrator create one
for you). If you are new to databases, figuring out how to do this
can actually be more difficult than learning how to program with
JDBC.
