Question

python3.6执行pymysql报错

\pymysql\__init__.py", line 90, in Connect
return Connection(*args, **kwargs)
File "C:\Users\lenovo\AppData\Local\Programs\Python\Python36\lib\site-packages\pymysql\connections.py", line 706, in __init__
self.connect()
File "C:\Users\lenovo\AppData\Local\Programs\Python\Python36\lib\site-packages\pymysql\connections.py", line 931, in connect
self._get_server_information()
File "C:\Users\lenovo\AppData\Local\Programs\Python\Python36\lib\site-packages\pymysql\connections.py", line 1245, in _get_server_information
packet = self._read_packet()
File "C:\Users\lenovo\AppData\Local\Programs\Python\Python36\lib\site-packages\pymysql\connections.py", line 987, in _read_packet
packet_header = self._read_bytes(4)
File "C:\Users\lenovo\AppData\Local\Programs\Python\Python36\lib\site-packages\pymysql\connections.py", line 1033, in _read_bytes
CR.CR_SERVER_LOST, "Lost connection to MySQL server during query")
pymysql.err.OperationalError: (2013, 'Lost connection to MySQL server during query')

Answer 1

折腾好半天的数据库连接，由于之前未安装 pip ，而且自己用的Python 版本为3.6. 只能用 pymysql 来连接数据库，下边 简单介绍一下 连接的过程，以及简单的增删改查操作。
1.通过 pip 安装 pymysql
进入 cmd 输入 pip install pymysql
回车等待安装完成；

安装完成后出现如图相关信息，表示安装成功。
2.测试连接
import pymysql #导入 pymysql ，如果编译未出错，即表示 pymysql 安装成功

简单的增删改查操作

示例表结构

2.1查询操作

[python] view plain copy
import pymysql #导入 pymysql

#打开数据库连接
db= pymysql.connect(host="localhost",user="root",
password="123456",db="test",port=3307)

# 使用cursor()方法获取操作游标
cur = db.cursor()

#1.查询操作
# 编写sql 查询语句 user 对应我的表名
sql = "select * from user"
try:
cur.execute(sql) #执行sql语句

results = cur.fetchall() #获取查询的所有记录
print("id","name","password")
#遍历结果
for row in results :
id = row[0]
name = row[1]
password = row[2]
print(id,name,password)
except Exception as e:
raise e
finally:
db.close() #关闭连接
2.2插入操作
[python] view plain copy
import pymysql
#2.插入操作
db= pymysql.connect(host="localhost",user="root",
password="123456",db="test",port=3307)

# 使用cursor()方法获取操作游标
cur = db.cursor()

sql_insert ="""insert into user(id,username,password) values(4,'liu','1234')"""

try:
cur.execute(sql_insert)
#提交
db.commit()
except Exception as e:
#错误回滚
db.rollback()
finally:
db.close()
2.3更新操作

[python] view plain copy
import pymysql
#3.更新操作
db= pymysql.connect(host="localhost",user="root",
password="123456",db="test",port=3307)

# 使用cursor()方法获取操作游标
cur = db.cursor()

sql_update ="update user set username = '%s' where id = %d"

try:
cur.execute(sql_update % ("xiongda",3)) #像sql语句传递参数
#提交
db.commit()
except Exception as e:
#错误回滚
db.rollback()
finally:
db.close()
2.4删除操作

[python] view plain copy
import pymysql
#4.删除操作
db= pymysql.connect(host="localhost",user="root",
password="123456",db="test",port=3307)

# 使用cursor()方法获取操作游标
cur = db.cursor()

sql_delete ="delete from user where id = %d"

try:
cur.execute(sql_delete % (3)) #像sql语句传递参数
#提交
db.commit()
except Exception as e:
#错误回滚
db.rollback()
finally:
db.close()