如何从SQL查询中提取单个列并将其添加到Python中的列表中

Question

I have a SQL query that will search a database and return a single row containing at least 3 different columns as follows:

SELECT
  `epg_num` AS `epgNum`,
  `service_key` AS `serviceKey`,
  `service_name` AS `channelName`
FROM `ssr_services`
WHERE `epg_num` = %(channelValue)s

I only require the Service Key to added to a list in my code.

The above SQL query cannot be amended as it is used by other things and I would prefer not to write a new query just for this one function. The above query is also a function in another module that I am calling to try and extract the Service Key.

The user will specify the epg_num when running the code. Which will then bring back a row in SQL showing the epg_num, service key and service name

Imports:

import sys
import os
import MySQLdb
from subprocess import check_output, CalledProcessError
from collections import OrderedDict

from UPnP.core.proxy import ServerProxy
from Data_Types import PlannerExportEvent, PlannerExportResponse, UpnpError, Result, Channel, Event, Shelf
from Database_Connection import FetchAll, FetchOne
from Decorators import ResetRetry, Suppress
from Logs import Logging
from Utilities import GetRecycID, GetRackID, Wait

The code I have at the moment is as follows:

        if epgNumsList:
            serviceKeysList = self.GetMultiChannelInfo(epgNumsList=epgNumsList)
            print(serviceKeysList)
            whereString = "(epg_num IN ({epgNumsList}) AND epg_num LIKE '___')".format(epgNumsList=','.join(epgNumsList))

Which uses the following:

    def GetMultiChannelInfo(self, epgNumsList=None):
        serviceKeys = []
        for epgNum in epgNumsList:
            retObj = self.GetChannelInfo(epgNum=epgNum)
            result = retObj.Result()
            if result:
                channelObj = retObj.Data()
                result = channelObj.serviceKey
                serviceKeys.append(result)
                print(result)

            else:
                print('Channel not found')
        print(serviceKeys)
        return Result(serviceKeys)

I am seeing the following error:

Traceback (most recent call last):
  File "C:\Users\MHE36\workspace\Scripts\SkyPlus__UPnP_Set_Recordings.py", line 42, in <module>
    upnp.BackgroundRecordings(recordings, epgNumsList, serviceKeysList, duration)
  File "C:\Users\MHE36\workspace\Libraries\SuperPlanner.py", line 1154, in BackgroundRecordings
    print(serviceKeysList)
  File "C:\Users\MHE36\workspace\Libraries\Data_Types.py", line 32, in __repr__
    return 'Result (Result: {result}, Data: {data}, NumFailures: {numFailures})'.format(result=self.result, numFailures=self.numFailures)
KeyError: 'data'

I think the trace back related to this bit of code from another module:

def __repr__(self):
        return 'Result (Result: {result}, Data: {data}, NumFailures: {numFailures})'.format(result=self.result, numFailures=self.numFailures)

Hopefully this gives enough detail but happy to provide more if needed.

Thanks in advance.

Answer 1

How are you executing that query? with pyodbc? then you can actually turn that particular row in to a dictionary

columns = [column[0] for column in cursor.description]
list_of_dict =[]
for dict in cursor.fetchall():
    list_of_dict.append(dict(zip(columns, dict)))

print that list_of_dict and you'll understand everything.

Note : you should not execute other queries before performing that code block because cursor will be refreshed.

What I suggest is you is that you access that list and return what you want at the time you are executing that query for some reason.