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[Java] 115. 코드 예제: JDBC를 활용하여 CRUD 해보기
1. Insert
2. Update
3. Delete
4. Select
1. Insert
package ch03;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
public class InsertExample {
public static void main(String[] args) {
String url="jdbc:mysql://localhost:3306/mydb2?serverTimezone=Asia/Seoul";
String user="root";
String password="asd123";
Connection connection=null;
Statement statement=null;
ResultSet resultSet=null;
try {
Class.forName("com.mysql.cj.jdbc.Driver");
connection=DriverManager.getConnection(url,user,password);
String query="insert into employee values(?,?,?,?,now())";
PreparedStatement preparedStatement=connection.prepareStatement(query);
preparedStatement.setInt(1, 8);
preparedStatement.setString(2, "가츠");
preparedStatement.setString(3, "IT");
preparedStatement.setString(4,"600000.00");
int rowCount=preparedStatement.executeUpdate();
System.out.println("rowCount : "+rowCount);
} catch (SQLException | ClassNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
// Connection 객체를 얻어서, insert 구문을 직접 만들어보자.
// mydb2 사용, employee 테이블에 값을 넣는 코드를 작성하세요.
} // end of main
}
2. Update
package ch03;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
public class UpdateExample{
public static void main(String[] args) {
String url = "jdbc:mysql://localhost:3306/mydb2?serverTimezone=Asia/Seoul";
String user = "root";
String password = "asd123";
// Connection 객체를 얻어서 삭제 구문을 직접 만들어 보세요.
// mydb2 사용, employee 테이블에 값을 넣는 코드를 작성하세요
Connection connection = null;
try {
Class.forName("com.mysql.cj.jdbc.Driver");
connection = DriverManager.getConnection(url, user, password);
String query = "SELECT * FROM employee WHERE id = ?";
PreparedStatement preparedStatement = connection.prepareStatement(query);
preparedStatement.setInt(1, 3);
ResultSet resultSet = preparedStatement.executeQuery();
while (resultSet.next()) {
System.out.println("User ID: " + resultSet.getInt("id"));
System.out.println("User Name: " + resultSet.getString("name"));
}
} catch (Exception e) {
}
} // end of main
}
package ch03;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
public class UpdateExample {
public static void main(String[] args) {
String url="jdbc:mysql://localhost:3306/mydb2?serverTimezone=Asia/Seoul";
String user="root";
String password="asd123";
Connection connection=null;
Statement statement=null;
ResultSet resultSet=null;
try {
Class.forName("com.mysql.cj.jdbc.Driver");
connection=DriverManager.getConnection(url,user,password);
String query = "update employee set name =? where id = ?";
PreparedStatement preparedStatement = connection.prepareStatement(query);
preparedStatement.setString(1, "그리피스");
preparedStatement.setInt(2,1);
int rowCount = preparedStatement.executeUpdate();
System.out.println("rowCount :" + rowCount);
} catch (SQLException | ClassNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
// Connection 객체를 얻어서, 수정 구문을 직접 만들어보세요.
// mydb2 사용, employee 테이블에 값을 넣는 코드를 작성하세요.
} // end of main
}
3. Delete
package ch03;
import java.beans.Statement;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Connection;
public class DeleteExample {
public static void main(String[] args) {
String url = "jdbc:mysql://localhost:3306/mydb2?serverTimezone=Asia/Seoul";
String user = "root";
String password = "asd123";
Connection connection = null;
Statement statement = null;
ResultSet resultSet = null;
try {
Class.forName("com.mysql.cj.jdbc.Driver");
connection = DriverManager.getConnection(url, user, password);
String query="delete from employee where name=?";
PreparedStatement preparedStatement=connection.prepareStatement(query);
preparedStatement.setString(1,"박영희");
int rowCount=preparedStatement.executeUpdate();
System.out.println("rowcount: "+rowCount);
} catch (ClassNotFoundException | SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
// Connection 객체를 얻어서, 삭제 구문을 직접 만들어보세요.
// mydb2 사용, employee 테이블에 값을 넣는 코드를 작성하세요.
} // end of main
}
4. Select
package ch03;
import com.mysql.cj.jdbc.ConnectionGroupManager;
import ch01.DTO.Client;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;
public class SelectExample {
public static void main(String[] args) throws SQLException {
String url="jdbc:mysql://localhost:3306/mydb2?serverTimezone=Asia/Seoul";
String user="root";
String password="asd123";
Connection connection=null;
Statement statement=null;
ResultSet resultSet=null;
try {
Class.forName("com.mysql.cj.jdbc.Driver");
connection=DriverManager.getConnection(url,user,password);
String query= "SELECT * from employee";
PreparedStatement preparedStatement=connection.prepareStatement(query);
resultSet=preparedStatement.executeQuery();
ArrayList<Employee> employeeList=new ArrayList<>();
while(resultSet.next()) {
Employee employee=new Employee();
employee.setName(resultSet.getString("name"));
employee.setDepartment(resultSet.getString("department"));
employee.setSalary(resultSet.getInt("Salary"));
employeeList.add(employee);
System.out.println("name:"+resultSet.getString("name"));
System.out.println("department: "+resultSet.getString("department"));
System.out.println("salary: "+resultSet.getInt("Salary"));
System.out.println("");
}
} catch (Exception e) {
// TODO: handle exception
}
// Connection 객체를 얻어서, 삭제 구문을 직접 만들어보세요.
// mydb2 사용, employee 테이블의 값을 수정하는 코드를 작성하세요.
} // end of main
}
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