无法连接到数据库错误，当在python中实现try / except语句时
无法连接到数据库错误，当在python中实现try / except语句时
提问于 2018-08-06 20:29:49
我下面有一个python脚本，它试图建立到sql数据库的连接。数据库有一些问题，我想让脚本尝试重新连接到数据库，所以我添加了try / except。然而，现在我收到错误消息"Unable to connect to database“。如果我去掉try / except语句，脚本就能很好地工作。如果有人能帮助我让try / except语句工作，我将不胜感激！
使用Try内部的连接更新了代码
from __future__ import print_function
try:
import psycopg2
except ImportError:
raise ImportError('\n\033[33mpsycopg2 library missing. pip install psycopg2\033[1;m\n')
sys.exit(1)
import re
import sys
import json
import pprint
outfilepath = "crtsh_output/crtsh_flat_file"
DB_HOST = 'crt.sh'
DB_NAME = 'certwatch'
DB_USER = 'guest'
#conn = psycopg2.connect("dbname={0} user={1} host={2}".format(DB_NAME, DB_USER, DB_HOST))
#cursor = conn.cursor()
def connect_to_db():
filepath = 'forager.txt'
conn = psycopg2.connect("dbname={0} user={1} host={2}".format(DB_NAME, DB_USER, DB_HOST))
cursor = conn.cursor()
with open(filepath) as fp:
unique_domains = ''
while True:
try:
for cnt, domain_name in enumerate(fp):
print("Line {}: {}".format(cnt, domain_name))
print(domain_name)
domain_name = domain_name.rstrip()
cursor.execute('''SELECT c.id, x509_commonName(c.certificate), x509_issuerName(c.certificate), x509_notBefore(c.certificate), x509_notAfter(c.certificate), x509_issuerName(c.certificate)$
FROM certificate c, certificate_identity ci WHERE
c.id= ci.certificate_id AND ci.name_type = 'dNSName' AND lower(ci.name_value) =
lower(%s) AND x509_notAfter(c.certificate) > statement_timestamp()''', (domain_name,))
unique_domains = cursor.fetchall()
pprint.pprint(unique_domains)
outfilepath = "crtsh1" + ".json"
with open(outfilepath, 'a') as outfile:
outfile.write(json.dumps(unique_domains, sort_keys=True, indent=4, default=str, ensure_ascii = False))
break
except:
pass
#print("\n\033[1;31m[!] Unable to connect to the database\n\033[1;m")
if __name__ == "__main__":
connect_to_db()回答 1
Stack Overflow用户
发布于 2018-08-06 22:33:58
你需要做几件事：
移动此代码：
conn = psycopg2.connect("dbname={0} user={1} host={2}".format(DB_NAME, DB_USER, DB_HOST))
cursor = conn.cursor()到你的try中，这样当它循环时，如果它死了，它将重新建立连接。如下所示：
try:
conn = psycopg2.connect("dbname={0} user={1} host={2}".format(DB_NAME, DB_USER, DB_HOST))
cursor = conn.cursor()
for cnt, domain_name in enumerate(fp):
print("Line {}: {}".format(cnt, domain_name))
print(domain_name)
domain_name = domain_name.rstrip()我会在连接之间抛出一个停顿。您的DBA可能需要在一段时间内检测太多连接，如下所示：
#at the top of your code
import time
#in your loop add:
time.sleep(1)页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/51707677
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