书写的代码：

1.导 pymysql 包

import pymysql

if name == 'main':

# 2.创建连接对象
conn = pymysql.connect(
    host='localhost',
    user="root",
    password='mysql',
    database='py',
    port=3306,
    charset='utf8')
# 3.创建游标对象 连接对象.cursor()
cursor = conn.cursor()
# 4.执行 SQL 语句
# 4.1 书写 SQL 语句
sql = 'select * from stu;'
# 4.2 执行 SQL 语句
# 游标对象.execute（sql 语句） 返回值是影响的行数
# 对于查询操作来说，查询出来的数据结果保存在游标对象中
row = cursor.execute(sql)
print(f'{row} rows in set')
# 获取查询结果,查询结果是元组类型
print(cursor.fetchone())   # 获取一条查询结果
# 对于游标中保存的数据，只能获取一次，获取之后就不能再次获取了
print('-' * 30)
print(cursor.fetchall())   # 获取所有的数据,类型是元组
# 5.关闭游标
cursor.close()
# 6.关闭连接对象
conn.close()

报错内容：
/Users/xiexiang/Downloads/代码/python/16.正则表达式/pythonProject/venv/bin/python /Users/xiexiang/Downloads/代码/python/16.正则表达式/pythonProject/222.py
Traceback (most recent call last):
File "/Users/xiexiang/Downloads/代码/python/16.正则表达式/pythonProject/venv/lib/python3.9/site-packages/pymysql/connections.py", line 644, in connect
sock = socket.create_connection(
File "/Library/Developer/CommandLineTools/Library/Frameworks/Python3.framework/Versions/3.9/lib/python3.9/socket.py", line 843, in create_connection
raise err
File "/Library/Developer/CommandLineTools/Library/Frameworks/Python3.framework/Versions/3.9/lib/python3.9/socket.py", line 831, in create_connection
sock.connect(sa)
ConnectionRefusedError: [Errno 61] Connection refused

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File "/Users/xiexiang/Downloads/代码/python/16.正则表达式/pythonProject/222.py", line 6, in
conn = pymysql.connect(
File "/Users/xiexiang/Downloads/代码/python/16.正则表达式/pythonProject/venv/lib/python3.9/site-packages/pymysql/connections.py", line 358, in init
self.connect()
File "/Users/xiexiang/Downloads/代码/python/16.正则表达式/pythonProject/venv/lib/python3.9/site-packages/pymysql/connections.py", line 711, in connect
raise exc
pymysql.err.OperationalError: (2003, "Can't connect to MySQL server on 'localhost' ([Errno 61] Connection refused)")

进程已结束，退出代码为 1