pymysql: 一次尝试，但无法捕获 multi-sql 错误

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conn = pymysql.connect(host='localhost',user='user',password='password',db='mydb',charset='utf8')
cur = conn.cursor(pymysql.cursors.DictCursor)
try:
    query = 'select * from test where id = 1;abcd'
    cur.execute(query)
    res = cur.fetchone()
    print(res)
except Exception as e:
    print(e)

try:
    query = 'select * from test where id = 2;'
    cur.execute(query)
    res = cur.fetchone()
    print(res)
except Exception as e:
    print(e)

代码生成结果如下：

{'name': '', 'score': 1.1, 'id': 1}
(1064, "You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'abcd' at line 1")

第一行{'name': '', 'score': 1.1, 'id': 1}来自第一个try...except...中;之前的第一个查询。然后错误消息来自第二个 try...except... 但它来自 sql 查询 abcd，这意味着第二个 try...except... 中的 cur.execute(query) 产生由于 abcd 和 select * from test where id = 2; 未执行的异常。

那么我怎样才能忽略 abcd 并使第二个查询按预期执行呢？

原始问题
我正在使用 python 构建 Web 服务器。我使用MySQL作为数据库，pymysql作为数据库的接口。

现在我遇到一个问题：
当某些sql查询由于;而出错时，即使我使用了try...except...，程序也会被阻止。这是一个例子：

import pymysql
import pymysql.cursors

conn = pymysql.connect(host='localhost',user='user',password='password',db='mydb',charset='utf8')
cur = conn.cursor(pymysql.cursors.DictCursor)
try:
    query = 'select * from test where id = 1;abcd'  <--- exception!
    cur.execute(query)
    res = cur.fetchone()
    print(res)
except Exception as e:
    print(e)

query = 'select * from test where id = 2;'
cur.execute(query)
res = cur.fetchone()
print(res)

如您所见，第一个 query 是非法的，因为 ;abcd 部分。所以会产生错误。但是， try...except... 无法捕获此异常，因为我发现 print(e) 未执行。这是我收到的消息：

{'score': 1.1, 'name': '', 'id': 1}
Traceback (most recent call last):
  File "db_mysql.py", line 23, in <module>
    cur.execute(query)
  File "/usr/local/lib/python3.5/site-packages/pymysql/cursors.py", line 161, in execute
    while self.nextset():
  File "/usr/local/lib/python3.5/site-packages/pymysql/cursors.py", line 103, in nextset
    return self._nextset(False)
  File "/usr/local/lib/python3.5/site-packages/pymysql/cursors.py", line 98, in _nextset
    conn.next_result(unbuffered=unbuffered)
  File "/usr/local/lib/python3.5/site-packages/pymysql/connections.py", line 860, in next_result
    self._affected_rows = self._read_query_result(unbuffered=unbuffered)
  File "/usr/local/lib/python3.5/site-packages/pymysql/connections.py", line 1057, in _read_query_result
    result.read()
  File "/usr/local/lib/python3.5/site-packages/pymysql/connections.py", line 1340, in read
    first_packet = self.connection._read_packet()
  File "/usr/local/lib/python3.5/site-packages/pymysql/connections.py", line 1014, in _read_packet
    packet.check_error()
  File "/usr/local/lib/python3.5/site-packages/pymysql/connections.py", line 393, in check_error
    err.raise_mysql_exception(self._data)
  File "/usr/local/lib/python3.5/site-packages/pymysql/err.py", line 107, in raise_mysql_exception
    raise errorclass(errno, errval)
pymysql.err.ProgrammingError: (1064, "You have an error in your SQL syntax;
check the manual that corresponds to your MySQL server version for
the right syntax to use near 'abcd' at line 1")

我无法理解为什么try...except... 无法捕获错误。此外，似乎产生错误的查询是 abcd，而不是 select * from test where id = 1;abcd。如果我是对的，我认为 ; 将此查询分为两个查询。

此外，如果我删除 ;，这意味着第一个查询变为 query = 'select * from test where id = 1abcd'，try...except... 可能会捕获错误，因此第二个查询可以按预期执行。

所以我的问题是：为什么 try...except... 无法捕获错误？我该怎么做才能处理所有 sql 错误，以便程序不会被阻止？

Answer 1

So my question is: why the try...except... can't catch the error? What could I do to handle all of sql errors so that the program won't be blocked?

也许有好的例外名称？

try:
    …
except pymysql.err.ProgrammingError as except_detail:
        print("pymysql.err.ProgrammingError: «{}»".format(except_detail))

查看 help(pymysql.err) 或 PyMySQL's Github

中的所有异常类型

pymysql: 一次尝试，但无法捕获 multi-sql 错误

pymysql: one try except can't catch multi-sql errors

python

mysql

sql-server

pymysql