Question

我正在尝试使用pandas.read_sql_query读取SQL查询。

几个星期前我没有遇到过这些问题。问题是当我阅读一些查询时，出现以下错误：

df = pd.read_sql_query(sql = query_string, con = engine)
---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
~\.conda\envs\test\lib\site-packages\sqlalchemy\engine\result.py in _fetchall_impl(self)
   1160         try:
-> 1161             return self.cursor.fetchall()
   1162         except AttributeError:

AttributeError: 'NoneType' object has no attribute 'fetchall'

During handling of the above exception, another exception occurred:

ResourceClosedError                       Traceback (most recent call last)
...
~\.conda\envs\test\lib\site-packages\sqlalchemy\engine\result.py in _non_result(self, default)
   1166         if self._metadata is None:
   1167             raise exc.ResourceClosedError(
-> 1168                 "This result object does not return rows. "
   1169                 "It has been closed automatically."
   1170             )

ResourceClosedError: This result object does not return rows. It has been closed automatically.

这仅在使用某些查询而不是其他查询时发生，因此我知道这不是我的连接。我在两个语句上都设置了SET NOCOUNT ON，并且都在使用临时表。谁能指导我为什么一个查询有效而另一个查询无效？两者都可以在SSMS中正常工作。我试图在下面提供两者的基本结构。第一个有效，第二个无效。

set nocount on
                                                                    
DECLARE      @var1  varchar(20)= 'sometext'                                                             
                                                                
IF OBJECT_ID('tempdb..#temp1', 'U') IS NOT NULL                                                                     
        DROP TABLE #temp1                                                                       
                                                                        
select * into  #temp1 from  some_function_view WHERE  [x] = @var1                                                                       
                                                                        
IF OBJECT_ID('tempdb..#temp2', 'U') IS NOT NULL                                                                     
        DROP TABLE #temp2                                                                       
select * into #temp2 FROM another_view JOIN ...                                                     
                                                                        
SELECT Main.[y]...                                                                                                                                      
FROM (                                                                      
                                                                        
    SELECT *                                                                                                                                    
    FROM another_view                                                                       
    JOIN...                                                                                                                                     
    WHERE...                                                                
    GROUP BY...
) Main                                                                      
    JOIN #temp2...

set nocount on

begin try drop table #temp1 end try begin catch end catch
begin try drop table #temp2 end try begin catch end catch
begin try drop table #temp3 end try begin catch end catch

DECLARE @x  int = 202007
DECLARE @y  int = 2016  

SELECT * into #temp1 FROM a_view

SELECT  * into #temp2       
FROM a_view     
JOIN (SELECT...FROM a_view WHERE...GROUP BY ...)


SELECT... into #temp3 FROM a_view       
JOIN... 
LEFT JOIN...
WHERE x = @x, y = @y... 
Group BY...

SELECT *

FROM #policy as FPFR        
    JOIN #temp1...
    JOIN #temp2...
    JOIN #temp3...
ORDER BY...

Answer 1

所以我知道了。我需要在我的SQL查询中包括“ SET ANSI_WARNINGS OFF” 和 “ SET NOCOUNT ON”。

仅拥有一个是不够的。两者的结合可以捕获SQL抛出的任何存储过程错误，以便Python可以成功读取它。

使用熊猫时的ResourceClosedError / AttributeError read_sql_query AttributeError：“ NoneType”对象没有属性“ fetchall”

1 个答案: