pymysql中.format
时间: 2023-11-06 08:54:19 浏览: 26
pymysql中没有.format方法。在pymysql中,可以使用%s来进行SQL语句的参数传递。例如,在执行update语句时,可以使用%s来替代要更新的字段值。示例代码如下:
```python
import pymysql
# 连接数据库
conn = pymysql.connect(host='localhost', user='root', password='123456', database='test')
cursor = conn.cursor()
# 定义要更新的值
field = '-'
# 执行SQL语句
sql = "UPDATE cnp.Test SET a='' WHERE b=%s"
cursor.execute(sql, (field,))
# 提交事务
conn.commit()
# 关闭连接
cursor.close()
conn.close()
```
在这个例子中,我们使用%s来代替要更新的字段值,然后在execute方法中传入一个元组,元组里面包含了要替换的值。这样可以避免SQL注入的问题,并且提高了代码的安全性。
相关问题
pymysql.err.DataError: (1366, "Incorrect decimal value: '嘉定老城' for column 'price' at row 1")
This error message suggests that there is an issue with the data being inserted into the 'price' column of a MySQL table using PyMySQL. Specifically, it appears that the value being inserted, which is '嘉定老城', is not a valid decimal value.
To fix this issue, you will need to ensure that the data being inserted into the 'price' column is in the correct format. In this case, it is likely that the 'price' column should only contain numerical values. You may need to modify your code to convert any non-numerical values to a valid decimal format before inserting them into the database.
Alternatively, you may need to modify the data type of the 'price' column in the MySQL table to allow for non-decimal values, such as a string or text data type. However, this will depend on the specific requirements of your application and data model.
写一个python的带参数的装饰器, 装饰一个sql查询, 捕获比如pymysql.err.OperationalError 如果出现Too many connections等异常,进行最多重试n次请求
好的,下面是一个带参数的装饰器,可以对 SQL 查询进行最多 n 次的重试:
```python
import pymysql
def retry(n):
def decorator(func):
def wrapper(*args, **kwargs):
for i in range(n):
try:
result = func(*args, **kwargs)
return result
except pymysql.err.OperationalError as e:
if "Too many connections" in str(e):
print("Got too many connections error. Retrying...")
else:
raise e
raise Exception("Failed to execute SQL query after {} retries.".format(n))
return wrapper
return decorator
```
其中,n 是最多重试的次数,func 是被装饰的函数,也就是 SQL 查询。在 wrapper 函数内部,我们使用了一个 for 循环来进行最多 n 次的重试,如果出现了 Too many connections 的异常,就打印出信息并继续重试,否则就将异常抛出。如果最终还是无法成功执行 SQL 查询,就抛出一个自定义的异常。