10. JDBCConnectTest

1. 데이터베이스 연동 프로그래밍 환경
    1) DB
    2) DB와 Java App을 연결하는 드라이버 : ojdbc8.jar 

2. 데이터베이스 접속 자바 클래스
    1) java.lang.Class          forName("클래스이름");                 
                                => JDBC 드라이버 로딩
    2) java.sql.DriverManager   getConnection(url, user, password);   
                                => DB Connection 객체 생성
                
                Connection      createStatement()  
                                => SQL문 실행하는 Statement 객체를 생성

                Statement       executeQuery(sql);
                                => SQL문을 실행해서 ResultSet 객체를 생성
                                executeUpdate(sql);   

                ResultSet       getString(), getInt()...
                                => 쿼리 실행결과를 반환