Welcome to the website of Davis Fiore

JDBC is a Java techonology to access databases. JDBC APIs allow a developer to load a particular JDBC driver, via a component called JDBC driver manager. The advantage of this is that you are not writing for a specific database and it's easy to switch.

Depending on the needs there are different kinds of JDBC drivers:

• JDBC-ODBC bridge drivers, where the driver calls a ODBC driver via JNI
• Native-API driver, which uses libraries to convert JDBC calls to native DB calls. Being written partly in Java and partly in native code, they are not very portable. (i.g. Oracle OCI)
• Network-protocol driver, which accesses the DB via application server
• Native-protocol driver, which connects directly to the DB over the network. Purely written in Java. At client side a separate driver is needed for each DB, but they are very fast.

This is an example of query using JDBC:

	try (Connection conn = 
			DriverManager.getConnection("jdbc:mysql://localhost:3306/school","root","");			
		Statement st = conn.createStatement(
			ResultSet.TYPE_SCROLL_SENSITIVE, ResultSet.CONCUR_UPDATABLE);
		ResultSet rs = st.executeQuery("select * from students");) {
			
		while(rs.next())
			System.out.println(rs.getString("firstName") + "\t" +
						rs.getString("lastName")
					);
		
	} catch (SQLException e) {
		// This is just an example... in a real application you would have to 
		// manage this exception.
		e.printStackTrace();
	}	

This is the way a writing operation is usually done:

	try (Connection conn = 
			DriverManager.getConnection("jdbc:mysql://localhost:3306/school","root","");			
		Statement st = conn.createStatement(
			ResultSet.TYPE_SCROLL_SENSITIVE, ResultSet.CONCUR_UPDATABLE);
		) {

		st.executeUpdate("update students set name=\"Bobo\" where name=\"Boby\"");
		
	} catch (SQLException e) {
		// This is just an example... in a real application you would have to 
		// manage this exception.
		e.printStackTrace();
	}

Use executeQuery() if the operation returns a ResultSet
Use execute() if the operation returns more than one ResultSet and retrieve them by calling Statement.getResultSet()
Use executeUpdate() if the operation is an update, insert or delete

There are three types of Statement you can use:

• Statement: used for SQL statements without parameters.
• PreparedStatement: used for SQL statements with parameters.
• CallableStatement: Used to execute stored procedures.