如何在短时间间隔内使用 python 从 Ubuntu 16.04 连接到 SQL Server 2016？

Question

我正在尝试使用 python 从 Ubuntu 16.04 虚拟机将数据写入 SQL Server 2016 Express 数据库。将通过 FreeTDS、UnixODBC、pyodbc 建立连接。

该程序通过 TCP 套接字获取一串传感器数据，对其进行格式化并将其写入（新的或现有的）table。这必须每 x 秒发生一次。因此我使用了 this answer.

该代码表现出一种奇怪的行为，我尝试并搜索了几个小时。它有时有效，有时无效。我认为问题出在 connection = pyodbc.connect(conn_str) 上，因为通常代码执行一次成功，然后卡在这一行。几分钟后出现错误：

connection = pyodbc.connect(conn_str)
Error: ('08S01', '[08S01] [unixODBC][FreeTDS][SQL Server]Unable to connect: Adaptive Server is unavailable or does not exist (20009) (SQLDriverConnect)')

问题可能与打开的连接有关，但它应该在脚本结束时关闭。你有解决方案吗？如何使用 try/except 函数捕获此类错误？请询问我是否应该提供更多信息。

预先感谢您的帮助！

这是代码：

import sys
import pyodbc
import socket
import re
from threading import Timer
import time

# Timer (see link above)
class InfiniteTimer():

def pi_to_sql():
    dsn = "sqlserverdatasource"
    user = "User"
    password = "Password"
    database = "MSSQL_DB"

    conn_str = "DSN=%s;UID=%s;PWD=%s;DATABASE=%s;" % (dsn, user, password, database)
    connection = pyodbc.connect(conn_str)
    cursor = connection.cursor()

    # Create TCP/IP socket (client)
    sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

    # Create connection with socket server (insert IP of server)
    server_address = ('XXX.XXX.XXX.XXX', 10000)
    sock.connect(server_address)

    # Sending order to server
    to_send = "send data"
    sock.sendall(to_send)

    # Receiving data (string, e.g. "DS18B20;28FF97FF841605C0;32.4375")
    data = sock.recv(1024)

    # Filter data using regex
    data_list = re.findall(r"(?P<name>\w{6,});(?P<address>[0-9A-F]{16,});(?P<value>-?\d+\.?\d+)",data,re.M)

    # Closing socket
    sock.close()

    sensor_cnt = len(data_list)

    i = 0

    # Write sensor data to new or existing table using a loop
    while i<=(sensor_cnt-1):
        s_address = data_list[i][1]
        s_value = data_list[i][2]
        act_datetime = time.strftime("%Y%m%d %H:%M:%S")
        table_name = "sensor_" + s_address

        sql_command = """IF (NOT EXISTS (SELECT *
FROM INFORMATION_SCHEMA.TABLES
WHERE TABLE_SCHEMA = 'dbo'
AND  TABLE_NAME = '{0:s}'))
BEGIN
CREATE TABLE dbo.{0:s}
(
Timestamp DATETIME2(0),
S_Value FLOAT
)
END
INSERT INTO dbo.{0:s} VALUES
(
'{1:s}','{2:s}'
)""".format(table_name,act_datetime,s_value)

        try:
            cursor.execute(sql_command)
            connection.commit()

        except pyodbc.ProgrammingError:
            print("error")
            connection.close()

        i = i+1

    cursor.close()
    connection.close()

    print("done")

# Calling timer class to execute code every 5s
t = InfiniteTimer(5, pi_to_sql)
t.start()

tsql -C（我用的是最新的 stable .tar.gz 来自 FreeTDS）

Compile-time settings (established with the "configure" script)
                        Version: freetds v1.00.27
         freetds.conf directory: /usr/local/etc
 MS db-lib source compatibility: no
    Sybase binary compatibility: no
                  Thread safety: yes
                  iconv library: yes
                    TDS version: 7.4
                          iODBC: no
                       unixodbc: yes
          SSPI "trusted" logins: no
                       Kerberos: no
                        OpenSSL: no
                         GnuTLS: no
                           MARS: no

/etc/odbc.ini

[sqlserverdatasource]
driver = /usr/local/lib/libtdsodbc.so
server = XXX.XXX.XXX.XXX
port = 61521
database = MSSQL_DB
tds_version = 7.4

isql -v sqlserverdatasource 用户密码

+---------------------------------------+
| Connected!                            |
|                                       |
| sql-statement                         |
| help [tablename]                      |
| quit                                  |
|                                       |
+---------------------------------------+
SQL>

Answer 1

你试过没有连接池吗？

conn_str = "DSN=%s;UID=%s;PWD=%s;DATABASE=%s;" % (dsn, user, password, database)
pyodbc.pooling = False
connection = pyodbc.connect(conn_str)
cursor = connection.cursor()

我过去曾看到过解决与 SQL 服务器的连接问题，原因如下：

https://github.com/mkleehammer/pyodbc/wiki/Features-beyond-the-DB-API#connection-pooling

祝你好运！

Answer 2

This thread 让我想到用我拥有管理员权限的另一个版本 (SQL Server 2014) 在本地服务器上测试代码。所以我确保对于每个列出的 IP 地址，Active 和 Enabled 都是 Yes。它现在正在工作。不幸的是，我不能准确地说出问题所在（如果它取决于 SQL 服务器 16 本身或配置或不兼容）。我希望这句话可能对某人有所帮助。

如何在短时间间隔内使用 python 从 Ubuntu 16.04 连接到 SQL Server 2016？

How to connect to SQL Server 2016 from Ubuntu 16.04 using python in short time intervals?

python

pyodbc

freetds

ubuntu-16.04

sql-server-2016-express