1. JDBC

2. A Basic MySQL Tutorial MySQL is an open source database management software that helps users store, organize, and retrieve data. It is a very powerful program with a lot of flexibility Once you have MySQL installed on your system you can access the MySQL shell by typing the following command into terminal: mysql -u root -p After entering the root MySQL password into the prompt, you will be able to start building your MySQL database.

3. How to Create and Delete a MySQL Database MySQL organizes its information into databases; each one can hold tables with specific data. You can quickly check what databases are available by typing: SHOW DATABASES; Creating a database is very easy: CREATE DATABASE database name; In MySQL, the phrase most often used to delete objects is Drop. You would delete a MySQL database with this command: DROP DATABASE database name;

4. How to Access a MySQL Database Once we have a new database, we can begin to fill it with information. The first step is to create a new table within the larger database.for this we have to open up the database we want to use USE employee; you can also see an overview of the tables that the database contains. SHOW tables; Since this is a new database, MySQL has nothing to show, and you will get a message that says, “Empty set”

5. How to Create a MySQL Table CREATE TABLE human_resource (id INT NOT NULL PRIMARY KEY, name VARCHAR(20), age int not null,hire_date DATE); CREATE TABLE finance (id INT NOT NULL PRIMARY KEY, name VARCHAR(20), sex char(1),hire_date DATE); take a look at how the table appears within the database using the SHOW TABLES; command:

6. We can remind ourselves about the table’s organization with this command: DESCRIBE human_resource; N.B MySQL command line does not pay attention to cases but the table and database names are case sensitive: potluck is not the same as POTLUCK or Potluck.

7. How to Add Information to a MySQL Table INSERT INTO human_resource values (123, ‘alemu', 23, '2009-09-14 ‘); INSERT INTO human_resource values (125, ‘kebede', 28, '2000-11-14 ‘); INSERT INTO finance values (111, ‘almaz', ‘F’, ‘1984-09-12 ‘); INSERT INTO finance values (112, ‘solomon', ‘M’, ‘2001-02-12 ‘); We can take a look at our table: mysql> SELECT * FROM human_resource;

8. Wampserver is a s/w bundle for mysql, php,apache and php my admin Php my admin is a web based application which helps you to manage mysql database server How to create a database,table,fields? How to view tables in a data base, fields in a table? How to create a user? Using php myadmin

9. JDBC is a collection of classes and interfaces(it is an API) which helps your java application to connect with any relational database systems (like oracle, sql server,mysql, ms-acess and soon) JDBC is an interface between your java application and the database system. It is to mean Java database connectivity JDBC was included in the java programming world very early as part of JDK 1.1 in 1997 since then it continues to be part of different releases of JDK

10. The history of JDBC is the history of added features and improved performance The original release (in 1997 )includes the main classes and interfaces that you find yourself using all the time. These are the connection interface-which let you make your initial connection with the database Statement interface-which incapsulates the SQL code ResultSet interface-Which returns data from the server Later versions of JDBC improved the features of the API. Like updating your data without SQL, Scrolling and more data types

11. Recent releases included more data type, the ability to get metadata i.e lists of table and column information from your database In more recent release JDBC 4.0 was released in java6 and it included the ability to load drivers automatically.(no more Class.forName())

12. Using JDBC drivers Applications that use JDBC API require drivers A JDBC driver is a software library that communicates between a java application and a database. All JDBC drivers use the same set of rules that is the API which is defined in java SE. A driver library package will contain specific implementation of the interfaces defined in the API e.g Connection,ResultSet,Statement,… Typically you get your driver packages from database vendors i.e mysql driver from mysql,oracle driver from oracle

13. There are 4 types of drivers distinguished by their architecture These are Type-1(JDBC-ODBC bridge),Type-2 (Native API driver),Type-3(network-protocol drivers),Type-4(java thin driver) Reading assignment  Differentiate the architectural difference between these drivers.  What is the advantage and pitfall observed on each driver type.

14. The most popular driver type is Type-4 driver which we use now for our JDBC application

15. To connect to mysql you need a java driver and you can get a free driver from www.mysql.com/downloads/ and look for connector/Jwww.mysql.com/downloads/ (the J stands for Java)—a JDBC driver that allows programs to use JDBC to interact with MySQL.

16. 1. Open a Command Prompt and start the database server by executing the command mysqld.exe. This command has no output—it simply starts the MySQL server. Do not close this window—doing so terminates the server. 2. Next, you’ll start theMySQL monitor so you can set up a user account, open another Command Prompt and execute the command mysql -h localhost -u root The -h option indicates the host (i.e., computer) on which the MySQL server is running—in this case your local computer (localhost). The -u option indicates the user account that will be used to log in to the server—root is the default user account that is created during installation to allow you to configure the server.Once you’ve logged in, you’ll see a mysql> prompt at which you can type commands to interact with the MySQL server.

17. At the mysql> prompt, type USE mysql; and press Enter to select the built-in database named mysql, which stores server information, such as user accounts and their privileges for interacting with the server. Each command must end with a semicolon. To confirm the command, MySQL issues the message “Database changed.” Next, you’ll add the dbuser user account to the mysql built-in database. The mysql database contains a table called user with columns that represent the user’s name, password and various privileges. To create the dbuser user account with the password dbpassword, execute the following commands from the mysql> prompt:

18. create user ‘dbuser'@'localhost' identified by ‘dbpassword'; grant select, insert, update, delete, create, drop, references,execute on *.* to ‘dbuser'@'localhost'; Type the command exit; to terminate the MySQL monitor.

19. Manipulating Databases with JDBC This section introduces how to connect to a database and query it. Create a user ‘dbuser’ with a password ‘dbpassword’ And login to the mysql prompt with this user and check that you have the database explorecalifornia If this database is not existing, import the SQL source (if you are using the command line, execute the explorecalifornia.sql script by using the source command. If you are using an IDE import the.sql script)-LAB session

20. import java.sql.Connection; import java.sql.DriverManager; import java.sql.SQLException; public class DbTest{ static final String USERNAME="dbuser"; static final String PASSWORD="dbpassword"; static final String CONN_STRING= "jdbc:mysql://localhost/exploreca lifornia"; public static void main(String[] args)throws SQLException { Connection conn=null; try{ conn=DriverManager.getConnecti on(CONN_STRING,USERNAME, PASSWORD); System.out.println("connected"); }catch(SQLException sqlException ) { sqlException.printStackTrace(); } // end catch finally{ if(conn !=null){ conn.close(); }

21. public static void main(String[] args)throws SQLException in place of this we can use the try- catch block as finally{ try { conn.close(); }catch ( Exception exception ) { exception.printStackTrace(); } //end of catch }//end of finally

22. For MYSQL you include the file mysql-connector-java- 5.1.29-bin.jar (in the C:\mysql-connector-java-5.1.29 directory)in your programs class path. So to execute the code C:\java3>javac DbTest.java C:\java3>java -classpath.;C:\mysql-connector-java- 5.1.29\mysql-connector-java-5.1.29-bin.jar DbTest How to include and locate the driver(mysql-connector- java-5.1.29-bin.jar) in IDE’s e.g Eclipse? LAB session In past versions of Java, programs were required to load an appropriate database driver before connecting to a database. JDBC 4.0 and higher support automatic driver discovery— you’re no longer required to load the database driver in advance.

23. public static void main(String[] args)throws SQLException { //Class.forName(“com.mysql.jdbc.Driver”); Connection conn=null; try { ….. If the period (.) at the beginning of the class path information is missing, the JVM will not look for classes in the current directory and thus will not find the DbTest class file. NO MORE!

24. Connecting to the Database a Connection object (package java.sql) referenced by Conn( An object that implements interface Connection )manages the connection between the Java program and the database. The program initializes connection with the result of a call to static method getConnection of class DriverManager (package java. sql), which attempts to connect to the database specified by its URL. Method get-Connection takes three arguments—a String that specifies the database URL, a String that specifies the username and a String that specifies the password.

25. The URL locates the database (possibly on a network or in the local file system of the computer). The URL jdbc:mysql://localhost/explorecalifornia specifies the protocol for communication (jdbc), the subprotocol for communication (mysql) and the location of the database (//localhost/explorecalifornia where localhost is the host running the MySQL server and explorecalifornia is the database name). The subprotocol mysql indicates that the program uses a MySQL-specific subprotocol to connect to the MySQL database. If the DriverManager cannot connect to the database, method getConnection throws a SQLException (package java.sql).

26. Figure below lists the JDBC driver names and database URL formats of several popular RDBMSs.

27. Creating a statement for executing queries import java.sql.Connection; import java.sql.DriverManager; import java.sql.SQLException; import java.sql.Statement; import java.sql.ResultSet; public class DbTest{ private static final String USERNAME="dbuser"; private static final String PASSWORD="dbpassword"; private static final String CONN_STRING= "jdbc:mysql://localhost/explorecalifornia"; public static void main(String[] args)throws SQLException { Connection conn=null; Statement stmt=null; ResultSet rs=null; try{ conn=DriverManager.getConnection(CONN_STRI NG,USERNAME,PASSWORD); stmt=conn.createStatement(); rs=stmt.executeQuery("select * from states"); while(rs.next() ) { for ( int i = 1; i <= 2; i++ ){ System.out.print(rs.getObject( i ) ); System.out.print("\t"); } System.out.println(); } // end while //System.out.println("connected"); }catch(SQLException sqlException ) { sqlException.printStackTrace(); } // end catch finally{ { rs.close(); stmt.close(); conn.close(); }

28. Creating a Statement for Executing Queries stmt = conn.createStatement(); invokes Connection method createStatement to obtain an object that implements interface Statement (package java.sql). The program uses the Statement object to submit SQL statements to the database. Executing a Query the Statement object’s executeQuery method is used to submit a query that selects all the states information from table states. This method returns an object that implements interface ResultSet and contains the query results. The ResultSet methods enable the program to manipulate the query result.

29. Processing a Query’s ResultSet ResultSetMetaData metaData = rs.getMetaData(); obtains the metadata for the ResultSet as a ResultSetMetaData (package java.sql) object. The metadata describes the ResultSet’s contents. Programs can use metadata programmatically to obtain information about the ResultSet’s column names. int numberOfColumns = metaData.getColumnCount(); uses ResultSetMetaData method getColumnCount to retrieve the number of columns in the ResultSet.

30. First, the program positions the ResultSet cursor (which points to the row being processed) to the first row in the ResultSet with method next. Method next returns boolean value true if it’s able to position to the next row; otherwise, the method returns false. Initially, a ResultSet cursor is positioned before the first row. A SQLException occurs if you attempt to access a ResultSet’s contents before positioning the ResultSet cursor to the first row with method next. If there are rows in the ResultSet, the for…loop extract and display the contents of each column in the current row. For simplicity, this example treats each value as an Object. We retrieve each column value with ResultSet method getObject then print the Object’s String representation. Unlike array indices, ResultSet column numbers start at 1.

31. How to get the column name and number of columns? import java.sql.ResultSetMetaData; rs = statement.executeQuery( "SELECT * from states" ); ResultSetMetaData metaData = rs.getMetaData(); int numberOfColumns = metaData.getColumnCount(); System.out.println( “States Table of explorecalifornia database:\n" ); for ( int i = 1; i <= numberOfColumns; i++ ) { System.out.print( metaData.getColumnName( i ) ); System.out.print(“\t”); } System.out.println(); while(resultSet.next() ) {

32. 32 Basic steps to use a database in Java 1.Establish a connection 2.Create JDBC Statements 3.Execute SQL Statements 4.GET ResultSet 5.Close connections

33. 33 1. Establish a connection import java.sql.*; Load the vendor specific driver – Class.forName(“com.mysql.jdbc.Driver”); – What do you think this statement does, and how? Dynamically loads a driver class, for mysql database Make the connection – Connection con = DriverManager.getConnection( " jdbc:mysql://localhost/explorecalifornia ", username, passwd); What do you think this statement does? Establishes connection to database by obtaining a Connection object

34. 34 2. Create JDBC statement(s) Statement stmt = con.createStatement() ; Creates a Statement object for sending SQL statements to the database

35. 35 Executing SQL Statements stmt.executeUpdate (“ INSERT INTO states VALUES ( ‘AA', ‘Addis Ababa' )”); stmt.executeUpdate (“ INSERT INTO states VALUES ( ‘DZ', ‘Debrezeit' )”); stmt.executeUpdate("delete from states where stateID='DZ'"); String str = " Create table Lehigh(SSN Integer not null, Name VARCHAR(32),Marks Integer) " ; stmt.executeUpdate(str);

36. 36 Get ResultSet String queryStates = " select * from states " ; ResultSet rs = Stmt.executeQuery(queryStates); while (rs.next()) { …… }

37. 37 Close connection rs.close(); stmt.close(); con.close();