Friday, 16 August 2013

JDBC - PreparedStatement Object Example

Following is the example which makes use of PreparedStatement along with opening and closing statments:
This sample code has been written based on the environment and database setup done in previous chapters.
Copy and past following example in JDBCExample.java, compile and run as follows:
//STEP 1. Import required packages
import java.sql.*;

public class JDBCExample {
// JDBC driver name and database URL
static final String JDBC_DRIVER = "com.mysql.jdbc.Driver";
static final String DB_URL = "jdbc:mysql://localhost/EMP";

// Database credentials
static final String USER = "username";
static final String PASS = "password";

public static void main(String[] args) {
Connection conn = null;
PreparedStatement stmt = null;
try{
//STEP 2: Register JDBC driver
Class.forName("com.mysql.jdbc.Driver");

//STEP 3: Open a connection
System.out.println("Connecting to database...");
conn
= DriverManager.getConnection(DB_URL,USER,PASS);

//STEP 4: Execute a query
System.out.println("Creating statement...");
String sql = "UPDATE Employees set age=? WHERE id=?";
stmt
= conn.prepareStatement(sql);

//Bind values into the parameters.
stmt
.setInt(1, 35); // This would set age
stmt
.setInt(2, 102); // This would set ID

// Let us update age of the record with ID = 102;
int rows = stmt.executeUpdate();
System.out.println("Rows impacted : " + rows );

// Let us select all the records and display them.
sql
= "SELECT id, first, last, age FROM Employees";
ResultSet rs = stmt.executeQuery(sql);

//STEP 5: Extract data from result set
while(rs.next()){
//Retrieve by column name
int id = rs.getInt("id");
int age = rs.getInt("age");
String first = rs.getString("first");
String last = rs.getString("last");

//Display values
System.out.print("ID: " + id);
System.out.print(", Age: " + age);
System.out.print(", First: " + first);
System.out.println(", Last: " + last);
}
//STEP 6: Clean-up environment
rs
.close();
stmt
.close();
conn
.close();
}catch(SQLException se){
//Handle errors for JDBC
se
.printStackTrace();
}catch(Exception e){
//Handle errors for Class.forName
e
.printStackTrace();
}finally{
//finally block used to close resources
try{
if(stmt!=null)
stmt
.close();
}catch(SQLException se2){
}// nothing we can do
try{
if(conn!=null)
conn
.close();
}catch(SQLException se){
se
.printStackTrace();
}//end finally try
}//end try
System.out.println("Goodbye!");
}//end main
}//end JDBCExample
Now let us compile above example as follows:
C:\>javac JDBCExample.java
C
:\>
When you run JDBCExample, it produces following result:
C:\>java JDBCExample
Connecting to database...
Creating statement...
Rows impacted : 1
ID
: 100, Age: 18, First: Zara, Last: Ali
ID
: 101, Age: 25, First: Mahnaz, Last: Fatma
ID
: 102, Age: 35, First: Zaid, Last: Khan
ID
: 103, Age: 30, First: Sumit, Last: Mittal
Goodbye!
C
:\>
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