Database and Java Database Connectivity
5 likes762 views
Databases organize data to support processes that require information. A database system includes users, data, hardware to store data, and software to manage storage and retrieval. JDBC is a Java API that defines how clients access databases. It provides methods for querying and updating relational databases. JDBC implementations establish a database connection using a driver, submit queries with a Statement object to retrieve results in a ResultSet, and close resources when done. Future work could involve using servlets to extend server capabilities and host database applications.
Database and Java Database Connectivity
- 1. Database and Java Database Connectivity Gary 2013/06/13
- 2. Outline • Database • Distributed database • Relational Database • JDBC • JDBC Implementation • Future Work
- 3. Database • What is database? – A database is an organized collection of data. The data is typically organized to model relevant aspects of reality (for example, the availability of rooms in hotels), in a way that supports processes requiring this information (for example, finding a hotel with vacancies).
- 4. Database • Database system consists of – User – Data – Hardware • Where data resides – Software • Database management system(DBMS) • Controls storage and retrieval
- 5. Database • The advantage of database – Reduce redundancy – Avoid inconsistency – Share data – Enforce standards – Security restrictions – Data integrity – Balance conflicting requirement
- 6. Database • Non-database systems – Each application has its own files • Redundant • Lack centralized control
- 7. Database • Data independence – Applications not dependent on how data stored or accessed – Applications can have different views of data – Change storage/retrieval strategy without changing applications • Data dependency – Change in storage or retrieval technique forces program change
- 8. Database • Database language – Host languages • Used to access database • Can use high-level languages – Java, C, C++, Visual Basic, COBOL, PL/I, Pascal – Database sublanguage(DSL) • Specifics of database objects and operations • Combination of – Data definition language(DDL) – Data manipulation language(DML)
- 9. Database • Embedding SQL statements in a host language
- 10. Distributed database • A distributed database is a database in which storage devices are not all attached to a common processing unit such as the CPU, controlled by a distributed database management system. It may be stored in multiple computers, located in the same physical location; or may be dispersed over a network of interconnected computers.
- 11. Distributed database • Pros – Local autonomy or site autonomy • a department can control the data about them (as they are the ones familiar with it) – Protection of valuable data • if there were ever a catastrophic event such as a fire, all of the data would not be in one place, but distributed in multiple locations – Modularity • systems can be modified, added and removed from the distributed database without affecting other modules – Continuous operation • even if some nodes go offline (depending on design, like backup)
- 12. Distributed database • Cons – Complexity – Economics – Security – Difficult to maintain integrity
- 13. Relational Database • A relational database is a database that has a collection of tables of data items, all of which is formally described and organized according to the relational model.
- 14. Relational Database • Composed of tables – Rows called records(tuples) – Columns are fields(attributes) • First field usually primary key – Unique for each record – Primary key can be more than one field – Cannot allow null values
- 16. Relational Database • Operations – Projection • Taking a subset of a table – Join • Combining tables to form a larger on (by foreign key)
- 17. Relational Database • Example of projection
- 18. Relational Database • Advantages of relational database – Tables easy to use, understand, and implement – Projection and join operations easy to implement – Easy to modify – Great clarity and visibility
- 19. JDBC • JDBC is an API for the Java programming language that defines how a client may access a database. It provides methods for querying and updating data in a database. JDBC is oriented towards relational databases. A JDBC-to-ODBC bridge enables connections to any ODBC-accessible data source in the JVM host environment.
- 21. JDBC • There are four type of JDBC – JDBC bridge – Native-API bridge – JDBC-Net – Native-Protocol
- 22. JDBC • JDBC bridge • Ex: Microsoft Access Database Java APP JDBC API JDBC-ODBC Bridge ODBC API ODBC Layer DB
- 23. JDBC • Native-API bridge Java APP JDBC API Native-API Bridge Native API DB
- 24. JDBC • JDBC-Net Java APP JDBC API JDBC-Net Middleware or Server DB
- 25. JDBC • Native-Protocol • Ex: MySQL Java APP JDBC API Native-Protocol DB
- 26. JDBC Implementation • Establish database
- 27. JDBC Implementation – Has classes and Interfaces for using relational databases – Implements interface Connection – Manages connection between database and program 4 import java.sql.*; 11 private Connection connection;
- 28. JDBC Implementation – Database URL(location) username to log in password – URL • Protocol for communcation(jdbc) • Subprotocol(odbc) • Database name(Books) 19 String url = "jdbc:odbc:Books"; 20 String username = "anonymous"; 21 String password = "guest";
- 29. JDBC Implementation – Static method forName () – Static method getconnection • Attempt connection to database • Name and password required 25 Class.forName( "sun.jdbc.odbc.JdbcOdbcDriver" ); 27 connection = DriverManager.getConnection( 28 url, username, password );
- 30. JDBC Implementation • Other JDBC driver usage – MySQL – Oracle – Sybase – Postgresql
- 31. JDBC Implementation – The statement object • Submits query to database – Returns resultset object containing results – Statement.executeUpdate • Change data in database – Statement.executeQuery • Only query 49 Statement statement; 55 statement = connection.createStatement(); 53 String query = "SELECT * FROM Authors"; 50 ResultSet resultSet; 56 resultSet = statement.executeQuery( query );
- 32. JDBC Implementation – Statement closed when done – Unlock database 58 statement.close();
- 33. Conclusion
- 34. Future Wrok • Servelets – A servlet is a Java programming language class used to extend the capabilities of a server. Although servlets can respond to any types of requests, they are commonly used to extend the applications hosted by web servers, so they can be thought of as Java Applets that run on servers instead of in web browsers.