JDBC Basics (In 20 Minutes Flat)

JDBC Basics
(In 20 Minutes Flat)
Craig S. Dickson

!

Agenda
• What is JDBC?

• Connecting to a database
• Creating & Updating data

• Querying data
• Deleting data

!

About Me

• Software Architect, currently consulting
with Adobe and BET

• 15 years software development
experience

• Sun Certified JavaEE Architect

!

Assumptions

• Basic understanding of JavaSE 6
• Basic understanding of relational
database concepts and SQL

!

What is JDBC?

• JDBC = Java Database Connectivity

• Provides basic API for connecting to
relational databases

• Part of JavaSE since version 1.1 (c. 1997)
• java.sql and javax.sql

!

Driver

String driver = “org.apache.derby.jdbc.EmbeddedDriver”;

try {
Class.forName(driver);
} catch (ClassNotFoundException e) {
e.printStackTrace();
}

* this is even easier in JavaSE 6

!

Connect
String connection_url = “jdbc:derby:uci_ext_db;create=true”;

Connection connection = null;
try {
connection = DriverManager.getConnection(connection_url);
// use the connection
} catch (SQLException e) {
} finally {
if (connection != null) {
try {
connection.close();
} catch (SQLException ignore) {
}
}
}

!

Create A Table
String sql = "create table candidates
(id int, name varchar(50), hired smallint)";

Statement statement = null;
try {
statement = connection.createStatement();
statement.execute(sql);
} finally {
if (statement != null) {
try {
statement.close();
}
}
}

!

Create Rows
String sql1 = "insert into candidates values
(777, 'Craig Dickson', 0)";
String sql2 = "insert into candidates values
(888, 'Bill Gates', 0)";

try {
statement.execute(sql1);
statement.execute(sql2);
} finally {
try {
statement.close();
}
}
}

!

Updating
String sql = "update candidates set hired=1
where name='Craig Dickson'";

try {
statement.executeUpdate(sql);
} finally {
try {
statement.close();
}
}
}

!

Selecting
String sql = "select * from candidates";

ResultSet resultSet = null;
try {
resultSet = statement.executeQuery(sql);
printResults(resultSet);
} finally {
if (resultSet != null) {
try {
resultSet.close();
}
}
}

!

Selecting (2)
private void printResults(ResultSet resultSet)
throws SQLException {

System.err.println("ID NAME HIRED? ");
System.err.println("---- -------------- -------");
while (resultSet.next()) {
String id = String.format("%-6s", resultSet.getInt(1));
String name = String.format("%-16s", resultSet.getString(2));
String hired = String.format("%-7s", resultSet.getBoolean(3));
System.err.println(id + name + hired);
}
}

!

Selecting (3)

ID NAME HIRED?
---- -------------- -------
777 Craig Dickson true
888 Bill Gates false

!

Deleting
String sql = "delete from candidates where id=888";

try {
statement.executeUpdate(sql);
} finally {
try {
statement.close();
}
}
}

!

In conclusion ...
• JDBC can be used to connect to relational
databases from Java programs

• Allows all basic CRUD operations and can
handle sophisticated multi-tier, multi-vendor
environments

• Copious amounts of error handling required

• Can unintentionally create a dependency to a
specific database vendor

!

Resources

• Oracle’s JDBC Guide
• http://download.oracle.com/javase/6/docs/technotes/guides/jdbc/
getstart/GettingStartedTOC.fm.html

• java.sql Package Javadocs
• http://download.oracle.com/javase/6/docs/api/java/sql/package-
summary.html

!

JDBC Basics (In 20 Minutes Flat)

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