자바 삭제 package main.java.com.study.jdbc.main.dml; import main.java.com.study.jdbc.util.DBConnection2; import java.sql.Connection; import java.sql.PreparedStatement; import java.sql.SQLException; import java.util.Scanner; public class test4 { public static void main(String[] args) { Scanner sc = new Scanner(System.in); System.out.print("삭제할 계정의 id 값을 입력하세요: "); int id = sc.nextInt(); Connection co..

package main.java.com.study.jdbc.main.dml; import main.java.com.study.jdbc.util.DBConnection2; import java.sql.Connection; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.SQLException; public class test3 { public static void main(String[] args) { Connection connection = DBConnection2.getInstance().getConnection(); String sql = "select * from study_mst "; try { Prepa..

데이터 베이스 안 여러개의정보 넣기 package main.java.com.study.jdbc.main.dml; import main.java.com.study.jdbc.util.DBConnection2; import java.sql.Connection; import java.sql.PreparedStatement; import java.sql.SQLException; import java.util.ArrayList; import java.util.List; import java.util.Scanner; public class test5 { public static void main(String[] args) { Scanner scanner = new Scanner(System.in); List name..

SELECT title, COUNT(1) FROM test_mst GROUP BY title; SELECT content, COUNT(1) FROM test_mst GROUP BY content; SELECT writer_id, COUNT(1) FROM test_mst GROUP BY writer_id; SELECT writer_id, COUNT(writer_id) FROM test_mst GROUP BY writer_id; SELECT *, (SELECT COUNT(1)FROM test_mst tm2 WHERE tm2.writer_id = tm.writer_id) FROM test_mst tm; SELECT tm.title AS '제목', tm.content AS '내용', tm.writer_id AS..

subject_mst INSERT INTO subject_mst VALUE (0, 'java'), (0, 'c'), (0, '영어'), (0, '수학'); student_mst INSERT INTO student_mst VALUE (0, 'a'), (0, 'b'), (0, 'c'), (0, 'd'); major_mst INSERT INTO major_mst VALUE (0,'컴공'), (0,'디자인'), (0,'경영'), (0,'전자'); major_dtl INSERT INTO major_dtl VALUE (0,500), (0,400), (0,300), (0,350); student_number_dtl INSERT INTO student_number_dtl VALUE (0,1), (0,2), (0,3),..