使用pandasql执行SQL查询报错：'str'对象无'_execute_on_connection'属性

问题 #

在Spyder IDE中运行以下代码时出现错误：

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)

错误信息：

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'

已安装最新版本的pandas、pandasql和sqlalchemy。

解决方法 #

原因 #

SQLAlchemy 2.0+版本移除了对直接传入字符串SQL语句给execute方法的支持，而当前pandasql版本未适配该变更，导致报错。

方案1：降级SQLAlchemy到兼容版本 #

在终端执行以下命令：

pip install sqlalchemy==1.4.49 --force-reinstall

方案2：修改代码适配SQLAlchemy 2.0+ #

导入SQLAlchemy的text函数包裹查询语句，并显式传递当前环境变量：

from pandasql import sqldf
import pandas as pd
from sqlalchemy import text

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

# 用text包裹SQL查询语句
query = text("SELECT * FROM df WHERE column1 > 1")
# 显式传入globals()作为环境变量
new_dataframe = sqldf(query, globals())

print(new_dataframe)

内容的提问来源于stack exchange，提问作者ciavam