Java Database Connectivity
Definition of
Java Database Connectivity
JDBCT is a JavaT API for executing SQL
statements. (As a point of interest, JDBC is a trademarked name and is
not an acronym; nevertheless, JDBC is often thought of as standing for
"Java Database Connectivity".) It consists of a set of classes and
interfaces written in the Java programming language. JDBC provides a
standard API for tool/database developers and makes it possible to write
database applications using a pure Java API.
Using JDBC, it is easy to send SQL
statements to virtually any relational database. In other words, with
the JDBC API, it isn't necessary to write one program to access a Sybase
database, another program to access an Oracle database, another program
to access an Informix database, and so on. One can write a single
program using the JDBC API, and the program will be able to send SQL
statements to the appropriate database. And, with an application written
in the Java programming language, one also doesn't have to worry about
writing different applications to run on different platforms. The
combination of Java and JDBC lets a programmer write it once and run it
anywhere
Introduction of Java Database Connectivity
Java, being robust, secure, easy to
use, easy to understand, and automatically Downloadable on a network, is
an excellent language basis for database applications. What is needed
is a way for Java applications to talk to a variety of different
databases. JDBC is the mechanism for doing this. JDBC extends what can
be done in Java. For example, with Java and the JDBC API, it is possible
to publish a web page containing an applet that uses information
obtained from a remote database. Or an enterprise can use JDBC to
connect all its employees (even if they are using a conglomeration of
Windows, Macintosh, and UNIX machines) to one or more internal databases
via an intranet.
With more and more programmers using
the Java programming language, the need for easy database access from
Java is continuing to grow. MIS managers like the combination of Java
and JDBC because it makes disseminating information easy and economical.
Businesses can continue to use their installed databases and access
information easily even if it is stored on different database management
systems. Development time for new applications is short. Installation
and version control are greatly simplified.
What Does JDBC Do?
Simply put, JDBC makes it possible to do three things:
1. establish a connection with a database
2. send SQL statements
3. process the results.
The following code fragment gives a basic example of these three steps:
Connection con = DriverManager.getConnection (
"jdbc:odbc:wombat", "login", "password");
Statement stmt = con.createStatement();
ResultSet rs = stmt.executeQuery("SELECT a, b, c FROM Table1");
while (rs.next()) {
int x = getInt("a");
String s = getString("b");
float f = getFloat("c");
}
JavaSoft provides three JDBC product components as part of the Java Developer's Kit (JDK):
. the JDBC driver manager,
. the JDBC driver test suite, and
. the JDBC-ODBC bridge.
The JDBC driver manager is the
backbone of the JDB architecture. It actually is quite small and simple;
its primary function is to connect Java applications to the correct
JDBC driver and then get out of the way