AttributeError：“str”对象没有属性“_execute_on_connection”

Question

我对以下代码有问题：

from pandasql import sqldf
import pandas as pd

df = pd.DataFrame({'column1': [1, 2, 3], 'column2': [4, 5, 6]})

query = "SELECT * FROM df WHERE column1 > 1"

new_dataframe = sqldf(query)

print(new_dataframe)

当我提交时，出现以下错误：

Traceback (most recent call last):

  File ~\AppData\Local\Programs\Spyder\Python\lib\site-packages\sqlalchemy\engine\base.py:1410 in execute
    meth = statement._execute_on_connection

AttributeError: 'str' object has no attribute '_execute_on_connection'


The above exception was the direct cause of the following exception:

Traceback (most recent call last):

  File ~\AppData\Local\Programs\Spyder\pkgs\spyder_kernels\py3compat.py:356 in compat_exec
    exec(code, globals, locals)

  File c:\users\yv663dz\downloads\untitled1.py:18
    new_dataframe = sqldf(query)

  File ~\AppData\Local\Programs\Spyder\Python\lib\site-packages\pandasql\sqldf.py:156 in sqldf
    return PandaSQL(db_uri)(query, env)

  File ~\AppData\Local\Programs\Spyder\Python\lib\site-packages\pandasql\sqldf.py:61 in __call__
    result = read_sql(query, conn)

  File ~\AppData\Local\Programs\Spyder\Python\lib\site-packages\pandas\io\sql.py:592 in read_sql
    return pandas_sql.read_query(

  File ~\AppData\Local\Programs\Spyder\Python\lib\site-packages\pandas\io\sql.py:1557 in read_query
    result = self.execute(*args)

  File ~\AppData\Local\Programs\Spyder\Python\lib\site-packages\pandas\io\sql.py:1402 in execute
    return self.connectable.execution_options().execute(*args, **kwargs)

  File ~\AppData\Local\Programs\Spyder\Python\lib\site-packages\sqlalchemy\engine\base.py:1412 in execute
    raise exc.ObjectNotExecutableError(statement) from err

ObjectNotExecutableError: Not an executable object: 'SELECT * FROM df WHERE column1 > 1'

我安装了最新版本的 pandas、pandasql 和 sqlalchemy，并使用 Spyder 作为 IDE。有人可以帮我吗？

Answer 1

SQLAlchemy 2.0（2023 年 1 月 26 日发布）要求原始 SQL 查询由sqlalchemy.text.

此错误消息的一般解决方案是将查询文本传递给sqlalchemy.text()

from sqlalchemy import text
...

query = text("SELECT * FROM some_table WHERE column1 > 1")

然而在这种情况下，OP 使用pandasql，它需要一个字符串。似乎没有一种直接的方法可以使 pandasql 与 SQLAlchemy >= 2.0 兼容，并且该包似乎未维护，因此唯一的解决方案是找到一个已解决问题的 fork（有一些），fork 该项目您自己修复它，或者使用 Python 包管理器降级您的 SQLAlchemy 安装。例如，如果您使用pip：

python3 -m pip install --upgrade 'sqlalchemy<2.0'