Java database connection(JDBC)

Chapter 7
Database connection
Java is a software development tool used to make Web, desktop and mobile applications.
Databases are the central component for dynamic content, so Java supports connecting to the database.
JDBC allows you to connect to a wide-range of databases (Oracle,MySQL, etc),
but we're going to use the in-built database you get with the Java/NetBeans software.
The database is called Java DB, a version ofApache Derby.
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
1. Establish a connection
import java.sql.*;
Load the vendor specific driver
Class.forName("org.apache.derby.jdbc.ClientDriver");
What do you think this statement does, and how?

Dynamically loads a driver class, for Java DB database
Make the connection
Connection con = DriverManager.getConnection( “localhoust”, username, passwd);
What do you think this statement does?
Establishes connection to database by obtaining
a Connection object
2. Create JDBC statement(s)
Statement stmt = con.createStatement() ;
Creates a Statement object for sending SQL statements to the database
3.Executing SQL Statements
String containt = "Insert into tablename
(columns list) values(values list)";
stmt.executeUpdate(containt);
4.Get ResultSet
String queryLehigh = "select * from tablename";
ResultSet rs = Stmt.executeQuery(queryLehigh);
//What does this statement do?
while (rs.next()) {
int ssn = rs.getInt(1);
String name = rs.getString(2);
int marks = rs.getInt(3);
} 5.Close connection
stmt.close();
con.close();
Statement st=conn.createStatement();
st.executeUpdate("INSERT INTO tablename (ID, NAME) VALUES (3, 'ds')");
System.out.println(“data is inserted to database");
} catch(SQLException ex)
{ ex.getMessage();
System.out.println(“data cannot saved");
} catch(ClassNotFoundException ee)
{ ee.getMessage();
}}} Example to select data
package databasecon;
import java.sql.*;
public class Databasecon {
public static void main(String[] args) throws ClassNotFoundException, SQLException {
try
{ Class.forName("org.apache.derby.jdbc.ClientDriver");
String x="jdbc:derby://localhost:1527/databasename";
String y=“username";
String z="password";
Connection conn = DriverManager.getConnection(x,y,z);
ResultSet rs=st.executeQuery("select * from tablename");

while(rs.next())
{
System.out.print(rs.getInt(“colomun1"));
System.out.println(rs.getString(“colomun2"));
}
}
}catch(SQLException ex)
{ ex.getMessage();
System.out.println(“cannot access");
}
catch(ClassNotFoundException ee)
{
ee.getMessage();
} }}
Example to update data
package databasecon;
import java.sql.*;
public class Databasecon {
public static void main(String[] args) throws ClassNotFoundException, SQLException {
try
{ Class.forName("org.apache.derby.jdbc.ClientDriver");
String x="jdbc:derby://localhost:1527/databasename";
String y=“username";
String z="password";
Connection conn = DriverManager.getConnection(x,y,z);
st.executeUpdate("update tablename set id=10,name='bre' where id=1");
System.out.println(“data updated");
} catch(SQLException ex)
{ ex.getMessage();
System.out.println(“data canot update");
}
catch(ClassNotFoundException ee)
{ ee.getMessage();
} }} Example to delete data
package databasecon;
import java.sql.*;
public class Databasecon {
public static void main(String[] args) throws ClassNotFoundException, SQLException {
try
{
Class.forName("org.apache.derby.jdbc.ClientDriver");
String x="jdbc:derby://localhost:1527/databasename";
String y=“username";
String z="password";
Connection conn = DriverManager.getConnection(x,y,z);