mysql 导出结果集乱码

SHOW VARIABLES LIKE 'character_set_%';
SHOW VARIABLES LIKE 'collation_%';

mysqldump -u username -p --default-character-set=utf8 database_name > export.sql

ALTER DATABASE database_name CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;
ALTER TABLE table_name CONVERT TO CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;

import mysql.connector

config = {
    'user': 'username',
    'password': 'password',
    'host': 'localhost',
    'database': 'database_name',
    'charset': 'utf8mb4'
}

cnx = mysql.connector.connect(**config)

import mysql.connector
import csv

config = {
    'user': 'username',
    'password': 'password',
    'host': 'localhost',
    'database': 'database_name',
    'charset': 'utf8mb4'
}

cnx = mysql.connector.connect(**config)
cursor = cnx.cursor()

query = "SELECT * FROM table_name"
cursor.execute(query)

with open('export.csv', 'w', newline='', encoding='utf-8') as csvfile:
    writer = csv.writer(csvfile)
    writer.writerow([i[0] for i in cursor.description])  # 写入列名
    writer.writerows(cursor.fetchall())

cursor.close()
cnx.close()