JDBC 연습하기

위 글은 김성박선생님의 자바 강의를 바탕으로 쓰여졌습니다.
더 자세한 내용은 아래 링크를 통해 알아보실 수 있습니다.

부부개발단 유투브

---

데이터 입력하기

Scanner를 통해 데이터를 입력받도록 하자.

package com.example.jdbcprj;

import java.sql.*;
import java.util.Scanner;

public class Program2 {
    public static void main(String[] args) throws SQLException {

        Scanner sc = new Scanner(System.in);

        String title = sc.nextLine();
        String writer_id = sc.nextLine();
        String content = sc.nextLine();

        Connection conn = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/testdb?useSSL=false&serverTimezone=Asia/Seoul&useUnicode=true&character_set_server=utf8mb4", "root","gkseogh1!23");
        String sql = "INSERT INTO notice(title, writer_id, content) VALUES (?,?,?)";

        // PreparedStatement
        PreparedStatement ps = conn.prepareStatement(sql);
        ps.setString(1, title);
        ps.setString(2,writer_id);
        ps.setString(3,content);

        int result = ps.executeUpdate();
        System.out.println(result);

        
        ps.close();
        conn.close();
        
    }
}

데이터 수정하기

위와 같은 쿼리문을 수정해 보도록 하자.

package com.example.jdbcprj;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import java.util.Scanner;

public class Program3 {
    public static void main(String[] args) throws SQLException {

        Scanner sc = new Scanner(System.in);
        System.out.println("Please input id");
        int id = Integer.parseInt(sc.nextLine());


        System.out.println("WRITE!!  title, writer_id, content  HERE!!!. ex) enter ");
        String title = sc.nextLine();
        String writer_id = sc.nextLine();
        String content = sc.nextLine();

        Connection conn = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/testdb?useSSL=false&serverTimezone=Asia/Seoul&useUnicode=true&character_set_server=utf8mb4", "root","gkseogh1!23");

        String sql = "UPDATE NOTICE SET title =?, content = ? , writer_id = ? where id = ?";

        // PreparedStatement
        PreparedStatement ps = conn.prepareStatement(sql);
        ps.setString(1, title);
        ps.setString(2,content);
        ps.setString(3,writer_id);
        ps.setInt(4, id);

        int result = ps.executeUpdate();
        System.out.println(result);

        ps.close();
        conn.close();

    }
}

• SQL문을 잘 못 입력해서 시간을 많이 버렸다. SQL문이 중요하다는 것을 알았다.

데이터 삭제하기

package com.example.jdbcprj;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import java.util.Scanner;

public class Program4 {
    public static void main(String[] args) throws SQLException {

        Scanner sc = new Scanner(System.in);
        System.out.println("Please delete for id");
        int id = Integer.parseInt(sc.nextLine());

        Connection conn = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/testdb?useSSL=false&serverTimezone=Asia/Seoul&useUnicode=true&character_set_server=utf8mb4", "root","gkseogh1!23");

        String sql = "DELETE FROM notice WHERE ID = ?";
        // PreparedStatement
        PreparedStatement ps = conn.prepareStatement(sql);
        ps.setInt(1, id);

        int result = ps.executeUpdate();
        System.out.println(result);

        ps.close();
        conn.close();

    }
}

• 이번에도 SQL문을 정확하게 입력하지 않아 오류가 발생하였다.
• SQL문은 중요하다.

---

• 참고영상:https://www.youtube.com/watch?v=7ZKEhluutOs&list=PLq8wAnVUcTFWxwoc41CqmwnO-ZyRDL0og&index=14