在 pandas 中运行 SQL 查询

Question

我是 SQL 查询的新手。我正在用 python 编写代码和查询数据库。下面是我的代码，我不确定代码的问题：

import pyodbc
import pandas as pd
import numpy as np
#import datetime
from pandas import ExcelWriter
from pandas import ExcelFile
df_lots=pd.DataFrame()

sql = """
DECLARE @carts NVARCHAR(25) = 'Large';
DECLARE @item_type NVARCHAR(50)= 'Produce';
DECLARE @read_point INT= 0;
DECLARE @item_type NVARCHAR(MAX)= N'';
SELECT @item_type+=N',' + [items]
    FROM
        (
            SELECT distinct D.items
                FROM [dbo].[ITEM_SET_COMPACT_VIEW] D
                JOIN [dbo].[Placement] E 
                ON D.items=E.items
                WHERE D.[items] LIKE 'Large'
            ) x
    ORDER BY items;
SET @item_type = STUFF(@item_type, 1, 1, '');
SELECT *
    FROM [dbo].[Get_Data](@item_type, @item_type, @read_point, 1, 0);
"""
try:
    mssql_connection = pyodbc.connect('''
    DRIVER=ODBC Driver 17 for SQL Server;
    SERVER=XXXXXXX;
    DATABASE=XXXXXX;
    UID=XXXXXXXX;
    PWD=XXXXXXXX;
    ''')

    with mssql_connection.cursor() as cursor:
        cursor.execute(sql )
        lots=cursor.fetchall()

except pyodbc.Error as ex:
    print(f"Unexpected error {ex}")
df_lots=pd.DataFrame(np.array(lots))

当我运行上面的代码时，它给了我以下错误：

意外错误没有结果。以前的 SQL 不是查询。

---------------------------------------------------------------------------
NameError                                 Traceback (most recent call last)
<ipython-input-1-e3e7b4c5dae4> in <module>
     45 except pyodbc.Error as ex:
     46     print(f"Unexpected error {ex}")
---> 47 df_lots=pd.DataFrame(np.array(lots))

NameError: name 'lots' is not defined

谁能帮我解决这个问题？？

Answer 1

变量lots 在try ... except 块内创建。当此块发生异常时，变量lots未定义，然后行

df_lots=pd.DataFrame(np.array(lots))

导致错误。