Java & MySQL - Sample Code

This chapter provides an example of how to create a simple java based application to access MySQL database. This will show you how to open a database connection, execute a SQL query, and display the results.
All the steps mentioned in this template example, would be explained in subsequent chapters of this tutorial.
There are following six steps involved in building a JDBC application −
Import the packages: Requires that you include the packages containing the JDBC classes needed for database programming. Most often, using import java.sql.* will suffice.
Import the packages: Requires that you include the packages containing the JDBC classes needed for database programming. Most often, using import java.sql.* will suffice.
Open a connection: Requires using the DriverManager.getConnection() method to create a Connection object, which represents a physical connection with the database.
Open a connection: Requires using the DriverManager.getConnection() method to create a Connection object, which represents a physical connection with the database.
Execute a query: Requires using an object of type Statement for building and submitting an SQL statement to the database.
Execute a query: Requires using an object of type Statement for building and submitting an SQL statement to the database.
Extract data from result set − Requires that you use the appropriate ResultSet.getXXX() method to retrieve the data from the result set.
Extract data from result set − Requires that you use the appropriate ResultSet.getXXX() method to retrieve the data from the result set.
Clean up the environment − Requires explicitly closing all database resources versus relying on the JVM's garbage collection.
Clean up the environment − Requires explicitly closing all database resources versus relying on the JVM's garbage collection.
This sample example can serve as a template when you need to create your own JDBC application in the future.
This sample code has been written based on the environment and database setup done in the previous chapter.
Copy and paste the following example in TestApplication.java, compile and run as follows −
import java.sql.*;

public class TestApplication {
   static final String DB_URL = "jdbc:mysql://localhost/TUTORIALSPOINT";
   static final String USER = "guest";
   static final String PASS = "guest123";
   static final String QUERY = "SELECT id, first, last, age FROM Employees";

   public static void main(String[] args) {
      // Open a connection
      try(Connection conn = DriverManager.getConnection(DB_URL, USER, PASS);
         Statement stmt = conn.createStatement();
         ResultSet rs = stmt.executeQuery(QUERY);) {
         // Extract data from result set
         while (rs.next()) {
            // Retrieve by column name
            System.out.print("ID: " + rs.getInt("id"));
            System.out.print(", Age: " + rs.getInt("age"));
            System.out.print(", First: " + rs.getString("first"));
            System.out.println(", Last: " + rs.getString("last"));
         }
      } catch (SQLException e) {
         e.printStackTrace();
      } 
   }
}
Now let us compile the above example as follows −
C:\>javac TestApplication.java
C:\>

When you run TestApplication, it produces the following result −
C:\>java TestApplication
ID: 100, Age: 18, First: Zara, Last: Ali
ID: 101, Age: 25, First: Mahnaz, Last: Fatma
ID: 102, Age: 30, First: Zaid, Last: Khan
ID: 103, Age: 28, First: Sumit, Last: Mittal
C:\>


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