How can I do this properly to be able to select in DBSelectQuery class?

I have 2 different classes. One is for the db connection and one is for querying. I want to be able to select a query in the DBSelectQuery Class by extending it to DBConnection Class. How can I do it properly?

public class DBSelectQuery extends DBConnection {
public static void main(String[] args) {
    selectCourier();
}
public static String selectCourier() {
    queryStmt += "SELECT * FROM courier";
    System.out.println(queryStmt);
    return queryStmt;
   }
}

public class DBConnection {
public static Connection con;
public static String queryStmt;
public static void main(String[] args) {
    // TODO Auto-generated method stub
    try {
        Class.forName("com.mysql.jdbc.Driver");
        con = DriverManager.getConnection("jdbc:mysql://localhost:3306/java_activity", "root", "root");
        System.out.println("Database Connected");
        Statement stmt = con.createStatement();
        ResultSet rs = stmt.executeQuery(queryStmt);
        while (rs.next())
            System.out.println(rs.getInt(1) + "  " + rs.getString(2));
        con.close();
    }

    catch (Exception e) {
        System.out.println(e);
    }

}

}