Friday, 16 August 2013

JDBC - CallableStatement Object Example

Following is the example which makes use of CallableStatement along with the followinggetEmpName() MySQL stored procedure:
Make sure you have created this stored procedure in your EMP Database. You can use MySQL Query Browser to get it done.
DELIMITER $$

DROP PROCEDURE IF EXISTS
`EMP`.`getEmpName` $$
CREATE PROCEDURE
`EMP`.`getEmpName`
(IN EMP_ID INT, OUT EMP_FIRST VARCHAR(255))
BEGIN
SELECT first INTO EMP_FIRST
FROM
Employees
WHERE ID
= EMP_ID;
END $$

DELIMITER
;
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;
CallableStatement 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 = "{call getEmpName (?, ?)}";
stmt
= conn.prepareCall(sql);

//Bind IN parameter first, then bind OUT parameter
int empID = 102;
stmt
.setInt(1, empID); // This would set ID as 102
// Because second parameter is OUT so register it
stmt
.registerOutParameter(2, java.sql.Types.VARCHAR);

//Use execute method to run stored procedure.
System.out.println("Executing stored procedure..." );
stmt
.execute();

//Retrieve employee name with getXXX method
String empName = stmt.getString(2);
System.out.println("Emp Name with ID:" +
empID
+ " is " + empName);
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...
Executing stored procedure...
Emp Name with ID:102 is Zaid
Goodbye!
C
:\>
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