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我下面的 python 代码有什么问题？

我想连接到我的数据库，选择一些信息。这些在列表列表中，我抓取列表并执行“select..from..where..IN”： 

 import pypyodbc
 connection = pypyodbc.connect('Driver={SQL Server};'
                                    'Server=X;'
                                    'Database=Y;'
                                    'uid=X;pwd=Y')
 cursor = connection.cursor()

 NbFiche=0
 L=[[4702, 3095, 3543], [2040, 2030, 2020], []]
 for i in range(0,3):
    log=L[i]


    if (log is not None):
        if (len(log)==3):                

            SQLCommand = ("select count(*) from PRODUCTION where  ID_TV IN (?) ")
            cursor.execute(SQLCommand,(log,))
            results = cursor.fetchone()
            NbFiche += results[0]

这是错误：

 Traceback (most recent call last):
      File "//Srvaktct-bur02/telecontact/TCT TRAVAIL/Pôle Fichier/AMIRA/STATISTIQUES/nimp.py", line 18, in <module>
        cursor.execute(SQLCommand,(log,))
      File "C:\Users\admin_fichier\AppData\Local\Programs\Python\Python35\lib\site-packages\pypyodbc-1.3.3-py3.5.egg\pypyodbc.py", line 1470, in execute
        self._BindParams(param_types)
      File "C:\Users\admin_fichier\AppData\Local\Programs\Python\Python35\lib\site-packages\pypyodbc-1.3.3-py3.5.egg\pypyodbc.py", line 1275, in _BindParams
        if param_types[col_num][0] == 'u':
    TypeError: 'type' object is not subscriptable

新代码（编辑）：

 import pypyodbc
connection = pypyodbc.connect('Driver={SQL Server};'
                              'Server=x;'
                                    'Database=y;'
                                    'uid=x;pwd=y')

cursor = connection.cursor()

NbFiche=0
L=[[4702, 3095, 3543], [2040, 2030, 2020]]
for log in L:
    log=tuple(log) # I also tried with a list

    SQLCommand = ("select count(*) from PRODUCTION where  ID_TV IN (?) ")
    cursor.execute(SQLCommand,(log,))
    results = cursor.fetchone()
    NbFiche += results[0]

编辑 ：

import pypyodbc
connection = pypyodbc.connect('Driver={SQL Server};'
                                  'Server=x;'
                                        'Database=y;'
                                        'uid=x;pwd=y')
cursor = connection.cursor()
NbFiche=0
L=[[4702, 3095], [2040, 2030, 2020]]
for log in L:
    SQLCommand = ("select count(*) from PRODUCTION where  ID_TV IN (?)")
    params = ','.join(map(str,log))
    cursor.execute(SQLCommand,params)
    results = cursor.fetchone()
    NbFiche += results[0]

结果如下：

Traceback (most recent call last):
  File "//Srvaktct-bur02/telecontact/TCT TRAVAIL/Pôle Fichier/AMIRA/STATISTIQUES/nimp.py", line 13, in <module>
    cursor.execute(SQLCommand,params)
  File "C:\Users\admin_fichier\AppData\Local\Programs\Python\Python35\lib\site-packages\pypyodbc-1.3.3-py3.5.egg\pypyodbc.py", line 1454, in execute
    raise TypeError("Params must be in a list, tuple, or Row")
TypeError: Params must be in a list, tuple, or Row
4

1 回答 1

0

我想是因为你有一个空列表：

L=[[4702, 3095, 3543], [2040, 2030, 2020], []]
                                           ^^

并且在使用 进行测试时if，即使列表为空，它也通过了测试，类似于以下示例：

>>> l = []
>>> if l is not None:
        print('l is not empty')


l is not empty

实际上这是错误的，因此，要解决此问题，请执行以下操作：

>>> if l:
        print('l is not empty')
    else:
        print('l is Empty')


l is Empty

因此，将您的测试表达式更改为：

if log:
    if len(log)==3:
        #...

编辑：

如果 is 的长度log是可变长度的，那么您可能必须首先构建字符串参数，然后将其传递给cursor.execute方法，这样：

SQLCommand = "select count(*) from PRODUCTION where ID_TV IN ({}) "
params = ','.join(map(str,log))
cursor.execute(SQLCommand.format(params))

编辑2：

如果参数是用户输入数据，则先前提出的解决方案会暴露于SQL_injections漏洞。所以更好的方法是将它们作为参数传递给cursor.execute方法：

L=[[4702, 3095, 3543], [2040, 2030, 2020]]
for log in L:
    if log:
        SQLCommand = "select count(*) from PRODUCTION where  ID_TV IN ?"
        cursor.execute(SQLCommand, tuple(log))

如果您有多个参数：

SQLCommand = "select ?, ? from PRODUCTION where ID_TV IN ?"
cursor.execute(SQLCommand, (p1, p2, tuple(log)))
于 2016-06-28T13:20:41.380 回答