How to Add a New Column to a Table Using JDBC API?

Java has its own API which JDBC API which uses JDBC drivers for database connections. JDBC API provides the applications-to-JDBC connection and JDBC driver provides a manager-to-driver connection.

Following are the 5 important steps to connect the java application to our database using JDBC.

1. Registering the Java class
2. Creating a connection
3. Creating a statement
4. Executing queries
5. Closing connection

Note: Load mysqlconnector.jar into your program.

Steps:

• Download MySQLConnect/J (JDBC connector jar file) from the following link https://dev.mysql.com/downloads/connector/j
• Select platform-independent in select OS option
• Copy mysql-connector-java-5.1.34-bin.jar file in your project
• Right-click on it, select Build Path ⇾ Configure Build path ⇾ libraries ⇾ Add JARS
• In JAR selection window, select mysql-connector-java-5.1.34-bin.jar library under your project
• Click OK

 Create a Database, add a table with records using MySQL cmd. 

Java

// Java program to add a column to a table using JDBC

// dont forget to import below package
import java.sql.*;

public class Database {

    // url that points to mysql database,
    // 'db' is database name
    static final String url
        = "jdbc:mysql://localhost:3306/db";

    public static void main(String[] args)
        throws ClassNotFoundException
    {
        try {

            // this Class.forName() method is user for
            // driver registration with name of the driver
            // as argument i have used MySQL driver
            Class.forName("com.mysql.jdbc.Driver");

            // getConnection() establishes a connection. It
            // takes url that points to your database,
            // username and password of MySQL connections as
            // arguments
            Connection conn = DriverManager.getConnection(
                url, "root", "1234");

            // create.Statement() creates statement object
            // which is responsible for executing queries on
            // table
            Statement stmt = conn.createStatement();

            // Executing the query, student is the table
            // name and age is the new column
            String query
                = "ALTER TABLE student ADD COLUMN age INT";

            // executeUpdate() is used for INSERT, UPDATE,
            // DELETE statements.It returns number of rows
            // affected by the execution of the statement
            int result = stmt.executeUpdate(query);

            // if result is greater than 0, it means values
            // has been added
            if (result > 0)
                System.out.println("new column added.");
            else
                System.out.println(
                    "unable to add a column.");

            // closing connection
            conn.close();
        }
        catch (SQLException e) {
            System.out.println(e);
        }
    }
}