尝试从表中获取不同的值，其中另一个字段=一个id而不是另一个。
select id from tbl1
where route = 28 but not = 30
id有多个条目，我试图找到只有路由28且没有路由30的id。以下是我尝试过的但没有成功：
select ID
FROM Table
Where route like '28' and route <> '30'
答案 0 :(得分：1)
select id
from tbl1
group by id
having sum(case when route = 28 then 1 else 0 end) > 0
and sum(case when route = 30 then 1 else 0 end) = 0
答案 1 :(得分：1)
另一种方法是使用import csv
from collections import OrderedDict
from xml.etree.ElementTree import ParseError
import collections
from __future__ import print_function
def get_clientresponses_2(filename = 's.csv'):
with open(filename, 'rU') as infile:
reader = csv.DictReader(infile) # read the file as a dictionary for each row ({header : value})
data = {}
for row in reader:
for header, value in row.items():
try:
data[header].append(value)
except KeyError:
data[header] = [value]
client_responses = data['E'] #returns a list
for client_response in client_responses:
xml_string = (''.join(client_response))
xml_string = xml_string.replace('&', '')
try:
root = ElementTree.XML(xml_string)
# print(root)
return root
except ET.ParseError:
print("catastrophic failure")
continue
def allocate_and_write_2():
with open(filename, 'r') as infile:
reader = csv.DictReader(infile) # read the file as a dictionary for each row ({header : value})
header = set()
results = []
# data = {} # this is not needed for the purpose of this organization
for row in reader:
for xml_data in get_clientresponses_2():
xml_dat = dict(flatten_dict(xml_data))
row.update(xml_dat) # just for XML data
results.append(row) # everything else
header.update(row.keys()) # can't forget headers
# print(row) # returns dictionary of key values pairs (headers : values)
# print(results) # returns list wrapper for dictionary
# print(headers) #returns set of all headers
headers_list = list(header)
# print(headers_list) #list form of set
with open('csv_output.csv', 'wt') as f:
writer = csv.writer(f)
writer.writerow(headers_list)
for row in results:
data = [row.get(x, '') for x in headers_list]
# print(data)
writer.writerow(data)
# writer.writerows(zip(headers_list, data))
：
NOT EXISTS如果条件变得更复杂或者您想要所有列，这种方法会更好。