Advanced Programming Collage of Information Technology University of Palestine, Gaza Prepared by: Mahmoud Rafeek Alfarra Lecture12: Accessing Databases with JDBC

2 Outlines يقول ابن مسعود: مرحبًا بالشتاء, تتنزل فيه البركة و يطول فيه الليل للقيام و يقصر فيه النهار للصيام

3 Outlines  SQL’s statement overview  Java DB connectivity (JDBC)  Connecting to and Querying a Database  More

4  A database is an organized collection of data.  There are many different strategies for organizing data to facilitate easy access and manipulation.  A database management system (DBMS) provides mechanisms for storing, organizing, retrieving and modifying data for many users.  Database management systems allow for the access and storage of data without concern for the internal representation of data. Introduction

5  Some popular relational database management systems (RDBMSs) are 1. Microsoft SQL Server, 2.Oracle, 3.Sybase, 4.IBM DB2, 5.MySQL. Introduction

6  Java programs communicate with databases and manipulate their data using the JDBC™API.  A JDBC driver enables Java applications to connect to a database in a particular DBMS and allows programmers to manipulate that database using the JDBC API.  JDBC is almost always used with a relational database.  However, it can be used with any table-based data source. Java DB connectivity 'JDBC'

7 SQL’s statement overview

8  The hardest thing about using JDBC is usually getting the JDBC drivers to connect to the database in the first place.  The principle difficulty is because we need to get three different things working together: 1.Our Oracle database, 2.Our Java development environment, and 3.The JDBC drivers to connect the Oracle database and our Java programs. Connecting to Database Oracle DB JDE JDBC

9  There are numerous options and alternatives for connecting, many of which you can explore in more reading, but for now we'll start with the basics.  These are the steps required to connect to the database:  Setting up the Oracle, Java, and JDBC environment  Importing the JDBC classes we need  Loading and registering the JDBC driver  Getting a Connection object from the driver Connecting to Database

10 Setting up JDBC enviro.  You should set your CLASSPATH environment variable to include the Oracle JDBC driver.  This is provided by Oracle in the [ORACLE_HOME]\jdbc\lib directory.  If you are using Windows NT/2000/XP, you can set CLASSPATH using the System applet in the Control Panel.  If a CLASSPATH variable does not already exist, start by choosing New. Type in CLASSPATH as the variable name and.;\[ORACLE_HOME] \jdbc\lib\classes12.zip as the variable value.

11 Setting up JDBC enviro

12 Importing the JDBC Classes  The Java compiler needs to import the JDBC classes we will be using.  At the top of our Java source file, we need to include the following import statements:  If the CLASSPATH hasn't been set correctly, the second import above will generate a complaint from the compiler, claiming that the package oracle.jdbc.driver does not exist. import java.sql.*; import oracle.jdbc.driver.*;

13 Loading and Registering the JDBC Driver  To load the JDBC driver requires two steps: 1.Loading the class and 2.Registering it with the DriverManager.  The DriverManager will automatically load the driver for us. DriverManager.registerDriver(new oracle.jdbc.OracleDriver());

14 Getting a Connection  The DriverManager is responsible for connecting us to resources.  When we want to use a resource, such as a database, we construct a Uniform Resource Locater (URL) and use it to request a Connection object from the DriverManager.  The DriverManager will search the registered drivers for one that can accept our URL.

15 Getting a Connection  Oracle provides two JDBC drivers: 1.An OCI driver and 2.A pure-Java thin driver;  Each of these accepts several different types of URLs.  We will use the thin driver with a URL of the following format: : : "

16 Sample Connection Program // TestConnection.java – Load JDBC and connect to database import java.sql.*; import oracle.jdbc.driver.*; public class TestConnection { public static void main(String [] vars){ Connection conn; try { DriverManager.registerDriver(new oracle.jdbc.OracleDriver()); // The following needs to be edited with your database specifics: conn = DriverManager.getConnection( "scott", "tiger"); } catch (SQLException e) { System.out.println("Caught: " + e); System.exit(1); } } }

17 Next Lecture isa 1.Executing SQL Statements 2.Executing SQL Queries 3.Large Objects—BLOBs and CLOBs 4.Stored Procedures 5.RowSet Interface

18 Thank You … Questions?!