Selecting Data using JDBC

Using Statement:

• Statement is suitable for executing simple SQL queries without parameters.

Steps to Execute a SELECT Query Using Statement:

1. Establish a Connection: Establish a connection to the database.

2. Create a Statement: Create a Statement object using the connection.

3. Execute Query: Execute the SQL SELECT query using the Statement.

4. Process Results: Retrieve and process the results obtained from the query.

Example Code using Statement (Java):

javaCopy codeimport java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;

public class StatementExample {
    public static void main(String[] args) {
        String jdbcUrl = "jdbc:mysql://localhost:3306/mydatabase";
        String username = "username";
        String password = "password";

        try (Connection connection = DriverManager.getConnection(jdbcUrl, username, password);
             Statement statement = connection.createStatement()) {

            String sqlQuery = "SELECT * FROM users";
            ResultSet resultSet = statement.executeQuery(sqlQuery);

            while (resultSet.next()) {
                String name = resultSet.getString("name");
                int age = resultSet.getInt("age");
                System.out.println("Name: " + name + ", Age: " + age);
            }

        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

Using PreparedStatement:

• PreparedStatement is used for executing parameterized SQL queries.

Steps to Execute a Parameterized SELECT Query Using PreparedStatement:

1. Establish a Connection: Establish a connection to the database.

2. Create a PreparedStatement: Create a PreparedStatement object with the parameterized query using the connection.

3. Set Parameters: Set the parameter values using setter methods of the PreparedStatement.

4. Execute Query: Execute the PreparedStatement.

5. Process Results: Retrieve and process the results obtained from the query.

Example Code using PreparedStatement (Java):

javaCopy codeimport java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;

public class PreparedStatementExample {
    public static void main(String[] args) {
        String jdbcUrl = "jdbc:mysql://localhost:3306/mydatabase";
        String username = "username";
        String password = "password";

        try (Connection connection = DriverManager.getConnection(jdbcUrl, username, password)) {
            String sqlQuery = "SELECT * FROM users WHERE age > ?";
            int minAge = 18;

            try (PreparedStatement preparedStatement = connection.prepareStatement(sqlQuery)) {
                preparedStatement.setInt(1, minAge);

                ResultSet resultSet = preparedStatement.executeQuery();

                while (resultSet.next()) {
                    String name = resultSet.getString("name");
                    int age = resultSet.getInt("age");
                    System.out.println("Name: " + name + ", Age: " + age);
                }
            }

        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}