Java Database Derby Instance 1

package com.han.ch20.q1;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import com.han.Derby;

public class UpdateStu {
	private static Connection conn;
	private static PreparedStatement ps;
	private static ResultSet rs;
	private static ResultSetMetaData rsmd; // ResultSetMetaData has not the close() method
	public static void main(String[] rgs){
		Derby.loadDriver();// As is said in the class Derby, this action is not necessary with a JRE 1.6 and later.
		try {
			// create database "ch20"
			conn=Derby.createDatabaseAndGetConnection("ch20", "", "");
			
			// drop the table "tb_emp" if it exists
			if(Derby.isTableExists("tb_emp", conn)){
				ps=conn.prepareStatement("drop table tb_emp");
				ps.execute();
			}
						
			// create a table "tb_emp" in this database
			ps=conn.prepareStatement("create table tb_emp(id int, name varchar(20), department varchar(20))");
			ps.execute();
			
			// add elements into the table
			ps=conn.prepareStatement("insert into tb_emp values(?,?,?)");
			ps.setInt(1, 1);
			ps.setString(2, "Jing LI");
			ps.setString(3, "Computer technology");
			ps.executeUpdate();
			ps.setInt(1, 2);
			ps.setString(2, "Hao LI");
			ps.setString(3, "Sales department");
			ps.executeUpdate();
			ps.setInt(1, 3);
			ps.setString(2, "Yuanyuan XIONG");
			ps.setString(3, "Copumter technology");
			ps.executeUpdate();
			ps.setInt(1, 4);
			ps.setString(2, "Mei LIU");
			ps.setString(3, "Sales department");
			ps.executeUpdate();
			
			// consult the information associated with the department "Sales department"
			ps=conn.prepareStatement("select * from tb_emp where department='Sales department'");
			rs=ps.executeQuery();
			
			// display the query results on the console
			rsmd=rs.getMetaData();
			int numberOfColumns=rsmd.getColumnCount();
			String[] columnNames=new String[numberOfColumns];
			String[] columnTypeNames=new String[numberOfColumns];
			int[] precisions=new int[numberOfColumns];
			for(int i=0;i<numberOfColumns;i++){
				columnNames[i]=rsmd.getColumnName(i+1);
				columnTypeNames[i]=rsmd.getColumnTypeName(i+1);
				precisions[i]=rsmd.getPrecision(i+1);
				System.out.println(columnNames[i]+" : "
									+columnTypeNames[i]+"("
									+precisions[i]+")");
			}
			for(int i=0;i<numberOfColumns;i++){
				String columnName=columnNames[i];
				if(columnName.length()>precisions[i]){
					columnName=columnName.substring(0, precisions[i]);
				}
				System.out.printf("%-"+precisions[i]+"s|",columnName);
			}
			System.out.println();
			while(rs.next()){
				for(int i=0;i<numberOfColumns;i++){
					System.out.printf("%-"+precisions[i]+"s|",rs.getObject(i+1));
				}
				System.out.println();
			}
			
			// close the opened resources
			rs.close();
			ps.close();
			conn.close();
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}finally{
			// perform a clean database closing
			Derby.shutdownDatabase("ch20");
			Derby.shutdownAll();
		}	
	}
}

package com.han;

import java.sql.Connection;
import java.sql.DatabaseMetaData;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Properties;

/**
 * The Embedded mode is limited by that we can't run simultaneously 
 * two programs (two JVM instances) using a same database (databaseName is the same).
 * <p>
 * But we can instead use the NetworkServer mode to avoid this case, 
 * it is to say the "Client/Server" mode.
 * In this mode, you have to first start the NetworkServer by this command :
 * <pre>
 * java org.apache.derby.drda.NetworkServerControl start [-h hostIP -p portNumber]
 * </pre>
 * Or use the API : 
 * <pre>
 * NetworkServerControl serverControl = new NetworkServerControl(InetAddress.getByName("myhost"),1621);
 * serverControl.shutdown();
 * </pre>
 * schema is above the table/view. In MySQL schema is equivalent to database. 
 * So in MySQL, create database==create schema, 
 * but create database is not applicable to Java Derby. 
 * <p>
 * In Derby, schema is also equivalent to a user name.
 * @author HAN
 *
 */
public class Derby {
	private static Connection con=null;
	private static String port=null;
	private static String ip=null;

	/**
	 * The port will be set to default: 1527
	 */
	public static void setPortToDefault(){
		port="1527";		
	}

	public static void setPort(String port){
		Derby.port=port;
	}

	public static void setServer(String ip){
		Derby.ip=ip;
	}

	/**
	 * This express loading driver is not necessary for Java 6 and later, JDBC 4.0 and later.
	 * Because it can be added automatically by <code>DriverManager</code> when connecting to a database.
	 */
	public static void loadDriver(){
		//load the driver
		if(port==null){
			if(ip!=null){
				System.out.println("You seem to have set an ip address, if so, you have also to assign a port, or else an embedded database will be automatically used");
			}
			try {
				Class.forName("org.apache.derby.jdbc.EmbeddedDriver");
				System.out.println("The embedded driver is successfully loaded");
			} catch (ClassNotFoundException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}else{
			try{
				Class.forName("org.apache.derby.jdbc.ClientDriver");
				System.out.println("The client driver is successfully loaded");
			}catch(ClassNotFoundException e){
				e.printStackTrace();
			}
		}
	}

	/**
	 * create and connect a database
	 * @param databaseName
	 * @param user
	 * @param password
	 * @return a connection to the URL 
	 * @throws SQLException 
	 */
	public static Connection createDatabaseAndGetConnection(String databaseName, String user, String password) throws SQLException{
		//create and connect the database
		Properties props=new Properties();
		props.put("user",user);	
		props.put("password",password);
		if(port==null){
			if(ip!=null){
				System.out.println("You seem to have set an ip address, if so, you have also to assign a port before loading the driver, or else an embedded database is automatically used");
			}
			con=DriverManager.getConnection("jdbc:derby:"+databaseName+";create=true", props);
			System.out.println("Connection is successfully established, it uses an Embedded database");
		}else if(ip==null){
			con=DriverManager.getConnection("jdbc:derby://localhost:"+port+"/"+databaseName+";create=true", props);
			System.out.println("Connection is sucessfully established, it uses an network database but stored in the local host via the port: "+port);
		}else{
			con=DriverManager.getConnection("jdbc:derby://"+ip+":"+port+"/"+databaseName+";create=true", props);
			System.out.println("Connection is sucessfully established, it uses an network database whose host ip is: "+ip+" and via the port: "+port);
		}
		return con;
	}

	/**
	 * Shut down a specified database. But it doesn't matter that later we could also connect to another database.
	 * Because the Derby engine is not closed.
	 * @param databaseName
	 */
	public static void shutdownDatabase(String databaseName){
		boolean gotSQLExc = false;
		if(port==null){	
			try {
				DriverManager.getConnection("jdbc:derby:"+databaseName+";shutdown=true");				
			} catch (SQLException se) {
				if ( se.getSQLState().equals("08006") ) {
					gotSQLExc = true;
				}
			}
			if (!gotSQLExc) {
				System.out.println("Database did not shut down normally");
			}  else  {
				System.out.println("Database: "+databaseName+" shut down normally");
			}
		}else if(ip==null){
			try {
				DriverManager.getConnection("jdbc:derby://localhost:"+port+"/"+databaseName+";shutdown=true");				
			} catch (SQLException se) {
				// TODO Auto-generated catch block
				if ( se.getSQLState().equals("08006") ) {
					gotSQLExc = true;
				}
			}
			if (!gotSQLExc) {
				System.out.println("Database did not shut down normally");
			}  else  {
				System.out.println("Database: "+databaseName+" shut down normally");
			}
		}else{
			try {
				DriverManager.getConnection("jdbc:derby://"+ip+":"+port+"/"+databaseName+";shutdown=true");	
			} catch (SQLException se) {
				if ( se.getSQLState().equals("08006") ) {
					gotSQLExc = true;
				}
			}
			if (!gotSQLExc) {
				System.out.println("Database did not shut down normally");
			}  else  {
				System.out.println("Database: "+databaseName+" shut down normally");
			}
		}
	}

	/**
	 * shut down all opened databases and close the Derby engine.
	 * The effect is that after the execution of this method, we will not permitted to use Derby again in the rest of our program.
	 * Or else, an exception of "can't find a suitable driver for [a database URL]" will be thrown.
	 * However, you can still use another approach to resolve this problem: newInstance()
	 * For example,
	 * <pre>
	 * Class.forName("org.apache.derby.jdbc.EmbeddedDriver").newInstance();
	 * </pre>
	 */
	public static void shutdownAll(){
		boolean gotSQLExc = false;
		try {
			DriverManager.getConnection("jdbc:derby:;shutdown=true");	
		} catch (SQLException se) {
			// TODO Auto-generated catch block
			if ( se.getSQLState().equals("XJ015") ) {
				gotSQLExc = true;
			}
		}
		if (!gotSQLExc) {
			System.out.println("Database did not shut down normally");
		}  else  {
			System.out.println("All databases shut down normally and Derby completely closed");
		}
	}

	/**
	 * Just connect to a database desired by providing the appropriate parameters.
	 * @param databaseName
	 * @param user
	 * @param password
	 * @return
	 * @throws SQLException 
	 */
	public static Connection getConnection(String databaseName, String user, String password) throws SQLException{
		if(port==null){
			if(ip!=null){
				System.out.println("You seem to have set an ip address, if so, you have also to assign a port before loading the driver, or else an embedded database is automatically used");
			}
			con=DriverManager.getConnection("jdbc:derby:"+databaseName,user,password);
			System.out.println("Connection is sucessfully established, it uses an Embedded database");
		}else if(ip==null){
			con=DriverManager.getConnection("jdbc:derby://localhost:"+port+"/"+databaseName,user,password);
			System.out.println("Connection is sucessfully established, it uses an network database but stored in the local host via the port: "+port);
		}else{
			con=DriverManager.getConnection("jdbc:derby://"+ip+":"+port+"/"+databaseName,user,password);
			System.out.println("Connection is sucessfully established, it uses an network database whose host ip is: "+ip+" and via the port: "+port);
		}
		return con;
	}

	public static HashSet<String> listAllTables(Connection con) throws SQLException{
		DatabaseMetaData meta = con.getMetaData();
		ResultSet res = meta.getTables(null, null, null, new String[]{"TABLE"});
		HashSet<String> set=new HashSet<String>();
		while (res.next()) {
			set.add(res.getString("TABLE_NAME"));
			//use TABLE_SCHEM to view all users or schemas
			//set.add(res.getString("TABLE_SCHEM"));
		}
		System.out.println("All the tables associated to current connection are :");
		System.out.println(set);
		return set;
	}

	public static boolean isTableExists(String table, Connection con) throws SQLException{
		if(listAllTables(con).contains(table.toUpperCase())){
			return true;
		}else{
			return false;
		}
	}

	public static HashSet<String> listAllSchemas(Connection con) throws SQLException{
		DatabaseMetaData meta = con.getMetaData();
		ResultSet res = meta.getSchemas(null, null);
		HashSet<String> set=new HashSet<String>();
		while (res.next()) {
			set.add(res.getString("TABLE_SCHEM"));
		}
		System.out.println("All the schemas associated to current connection are :");
		System.out.println(set);
		return set;
	}

	public static HashMap<String, String> listAllSchemasAndTables(Connection con) throws SQLException{
		DatabaseMetaData meta = con.getMetaData();
		ResultSet res = meta.getTables(null, null, null, new String[]{"TABLE"});
		HashMap<String, String> map=new HashMap<String, String>();
		while (res.next()) {
			map.put(res.getString("TABLE_SCHEM"),res.getString("TABLE_NAME"));
		}
		System.out.println("All the tables and their corresponding schemas associated to current connection are :");
		System.out.println(map);
		return map;
	}
}