Use JUnit unit test & transaction usage

Junit unit testing

@Test Annotations are only valid in methods , As long as you add this annotation , You can run it directly .（import org.junit.Test）

Business

Only when everything is right , Before committing the transaction , The database changes accordingly , Ensure the safety of data operation .
$1.$ Open transaction

// Notify the database to open the transaction ,false  Turn on 
connection.setAutoCommit(false);

$2.$ Transaction submission

connection.commit();

$3.$ Transaction rollback

// If there is an anomaly , Tell the database to roll back the transaction 
connection.rollback();

$4.$ Closing transaction

connection.close();

example （ bank transfer ）

$1.$ Use 1/0 Expressions to make mistakes ;
$2.$ Do not open transaction , Transfer failed and cannot be rolled back , That is, both parties lost the money transferred ;
$3.$ Open transaction , Through try-catch Roll back , Transfer between both parties failed , Maintain the original state .

package com.tl.study01;

import org.junit.Test;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;

/** * @author tl *  Business   Roll back  Junit unit testing  */
public class TestJdbc04 {
    

    @Test
    public void test() {
    
        // Configuration information 
        //useUnicode=true&characterEncoding=utf-8  Solve the Chinese garbled code 
        String url="jdbc:mysql://localhost:3306/jdbc_study?useUnicode=true&characterEncoding=utf-8";
        String username = "root";
        String password = "123";

        Connection connection = null;

        //1. The load driver 
        try {
    
            Class.forName("com.mysql.jdbc.Driver");
            //2. Connect to database , On behalf of the database 
            connection = DriverManager.getConnection(url, username, password);

            //3. Notify the database to open the transaction ,false  Turn on 
            connection.setAutoCommit(false);

            String sql = "update account set money = money-100 where name = 'A'";
            connection.prepareStatement(sql).executeUpdate();

            // Making mistakes 
            int i = 1/0;

            String sql2 = "update account set money = money+100 where name = 'B'";
            connection.prepareStatement(sql2).executeUpdate();

            connection.commit();// Two of the above SQL It's all done , Just commit the business ！
            System.out.println("success");
        } catch (Exception e) {
    
            try {
    
                // If there is an anomaly , Tell the database to roll back the transaction 
                connection.rollback();
            } catch (SQLException e1) {
    
                e1.printStackTrace();
            }
            e.printStackTrace();
        }finally {
    
            try {
    
                connection.close();
            } catch (SQLException e) {
    
                e.printStackTrace();
            }
        }
    }

}