MySQL 连接器方法“fetchone”和“fetchmany”不符合 PEP 249

Question

With Python 3.6.2 and MySQL Connector 2.1.6 package on Windows 10，不调用数据库游标的 execute 方法，或在 non 上调用它SELECT 语句（CREATE、DROP、ALTER、INSERT、DELETE、UPDATE 等）产生以下结果:

>>> import mysql.connector
>>> session = mysql.connector.connect(user = "root", database = "mysql")
>>> cursor = session.cursor()
>>> cursor.fetchone()
>>> cursor.fetchmany()
[]
>>> cursor.fetchall()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "C:\Users\Maggyero\AppData\Local\Programs\Python\Python36-32\lib\site-packages\mysql\connector\cursor.py", line 891, in fetchall
    raise errors.InterfaceError("No result set to fetch from.")
mysql.connector.errors.InterfaceError: No result set to fetch from.
>>> cursor.execute("CREATE TABLE test (x INTEGER)")
>>> cursor.fetchone()
>>> cursor.fetchmany()
[]
>>> cursor.fetchall()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "C:\Users\Maggyero\AppData\Local\Programs\Python\Python36-32\lib\site-packages\mysql\connector\cursor.py", line 891, in fetchall
    raise errors.InterfaceError("No result set to fetch from.")
mysql.connector.errors.InterfaceError: No result set to fetch from.

PEP 249 明确说明 fetchone、fetchmany 和 fetchall 方法：

An Error (or subclass) exception is raised if the previous call to .execute*() did not produce any result set or no call was issued yet.

那么为什么 fetchone 和 fetchmany 不引发像 fetchall 这样的异常？

Answer 1

我在 bugs.mysql.com 上提交了 bug report，该错误已在 MySQL Connector/Python 8.0.23.

中修复

MySQL 连接器方法“fetchone”和“fetchmany”不符合 PEP 249

MySQL Connector methods `fetchone` and `fetchmany` are not PEP 249 compliant

python

mysql

mysql-connector

pep