1. 12/6/2015B.Ramamurthy1 Java Database Connectivity B.Ramamurthy

2. 12/6/2015B.Ramamurthy2 Introduction Most popular form of database system is the relational database system. Examples: MS Access, Sybase, Oracle, MS Sequel Server. Structured Query Language (SQL) is used among relational databases to construct queries. These queries can be stand-alone or embedded within applications. This form of SQL is known as embedded SQL.

3. 12/6/2015B.Ramamurthy3 Simple Database Application APPLICATIONAPPLICATION DBMSDB Ex: Access Oracle Sybase

4. 12/6/2015B.Ramamurthy4 Multi-Databases APPLICATIONAPPLICATION DBMS 1 DBMS 2 DBMS 3 DB

5. 12/6/2015B.Ramamurthy5 Standard Access to DB APPLICATIONAPPLICATION DRIVERMGRDRIVERMGR DBMS Driver 1 DBMS Driver 2 DBMS Driver 3 DBMS 1 DBMS 2 DBMS 3 DB

6. 12/6/2015B.Ramamurthy6 ODBC Architecture Application Class1Class2 Driver Manager DriverType1DriverType2DriverType3 DataSource2 DataSource1 DataSource3 ODBC

7. 12/6/2015B.Ramamurthy7 Open Database Connectivity (ODBC) Standard ODBC standard is an interface by which application programs can access and process SQL databases in a DBMS-independent manner. It contains: A Data Source that is the database, its associated DBMS, operating system and network platform A DBMS Driver that is supplied by the DBMS vendor or independent software companies A Driver Manager that is supplied by the vendor of the O/S platform where the application is running

8. 12/6/2015B.Ramamurthy8 ODBC Interface It is a system independent interface to database environment that requires an ODBC driver to be provided for each database system from which you want to manipulate data. The database driver bridges the differences between your underlying system calls and the ODBC interface functionality.

9. 12/6/2015B.Ramamurthy9 An Example ApplicationDriverManager Sybase drivermSQL driverInformix driver odbc standard API

10. 12/6/2015B.Ramamurthy10 Application in Java Application in Java DriverManager Sybase drivermSQL driverInformix driver odbc standard API jdbc API

11. 12/6/2015B.Ramamurthy11 Java Support for ODBC : JDBC When applications written in Java want to access data sources, they use classes and associated methods provided by Java DBC (JDBC) API. JDBC is specified an an “interface”. An interface in Java can have many “implementations”. So it provides a convenient way to realize many “drivers”

12. 12/6/2015B.Ramamurthy12 Java Support for SQL Java supports embedded SQL. Also it provides an JDBC API as a standard way to connect to common relational databases. You need a JDBC:ODBC bridge for using the embedded SQL in Java. Java.sql package and an extensive exception hierarchy. We will examine incorporating this bridge using sample code.

13. 12/6/2015B.Ramamurthy13 Data Source Local relational database; Ex: Oracle Remote relational database on a server; Ex: SQLserver On-line information service; Ex: Dow Jones, Customer database

14. 12/6/2015B.Ramamurthy14 Data Source and Driver Data source is the data base created using any of the common database applications available. Your system should have the driver for the database you will be using. For example your Windows system should have the MS Access Driver. There are a number of JDBC drivers available. Information on installing them is available at : http://industry.java.sun.com/products/jdbc/drivers

15. 12/6/2015B.Ramamurthy15 JDBC Components Driver Manager: Loads database drivers, and manages the connection between application & driver. Driver: Translates API calls to operations for a specific data source. Connection: A session between an application and a driver. Statement: A SQL statement to perform a query or an update operation. Metadata: Information about the returned data, driver and the database. Result Set : Logical set of columns and rows returned by executing a statement.

16. 12/6/2015B.Ramamurthy16 JDBC Classes Java supports DB facilities by providing classes and interfaces for its components DriverManager class Connection interface (abstract class) Statement interface (to be instantiated with values from the actual SQL statement) ResultSet interface

17. 12/6/2015B.Ramamurthy17 Driver Manager Class Provides static, “factory” methods for creating objects implementing the connection interface. Factory methods create objects on demand when a connection is needed to a DB driver, DriverManager does it using it factory methods.

18. 12/6/2015B.Ramamurthy18 Connection interface Connection class represents a session with a specific data source. Connection object establishes connection to a data source, allocates statement objects, which define and execute SQL statements. Connection can also get info (metadata) about the data source.

19. 12/6/2015B.Ramamurthy19 Statement interface Statement interface is implemented by the connection object. Statement object provides the workspace for SQL query, executing it, and retrieving returned data. SELECT {what} FROM {table name} WHERE {criteria} ORDER BY {field} Queries are embedded as strings in a Statement object. Types: Statement, PreparedStatement, CallableStatement

20. 12/6/2015B.Ramamurthy20 ResultSet interface Results are returned in the form of an object implementing the ResultSet interface. You may extract individual columns, rows or cell from the ResultSet using the metadata.

21. 12/6/2015B.Ramamurthy21 JDBC Application Architecture Application Connection Driver Manager Driver DataSource Statement Result Set

22. 12/6/2015B.Ramamurthy22 JDBC Programming Steps Import necessary packages; Ex: import java.sql.*; Load JDBC driver(driver should have been installed) Data source and its location should have been registered. Allocate Connection object, Statement object and ResultSet object Execute query using Statement object Retrieve data from ResultSet object Close Connection object.

23. 12/6/2015B.Ramamurthy23 Identifying Data Sources It is specified using URL format. : : Example(for local source): jdbc:odbc:tech_books Alternatively, for remote connection, jdbc:odbc://bina.cse.buffalo.edu:4333/tech_boo ks

24. 12/6/2015B.Ramamurthy24 Summary JDBC API of Java language conforms to the ODBC standard. It supports ODBC by providing classes/interfaces for driver manager, driver, connection, statement and resultset and others. You can access various components in JDBC by instantiating or implementing objects and accessing their methods.