在Python脚本中无法在本地数据库上进行Firebird连接 [英] Firebird connection on a local database impossible within a Python script

问题描述

我可以使用Firebird ISQL工具(Firebird 3.0.4)通过以下命令连接到我的Firebird数据库: connect "C:\Documents\database.db" user 'USER' password 'PASSWORD';

当我想在Python脚本(Windows10 64位版本上为Python v3.7.7)上，在包括fdb v2.0.1甚至firebirdsql v1.1.3的虚拟环境中执行此操作时，我不能，而且我系统地获得了错误.

import fdb
con = fdb.connect(database="C:\Documents\database.db", user='USER' password='PASSWORD'')

DatabaseError :('连接数据库时出错:\ n- SQLCODE: -902 \ n-无法完成主机"xnet://Global \ FIREBIRD"的网络请求.'，-902，335544721)

或

con = fdb.connect(host='localhost', database="D:\Documents\database.db", user= 'USER' password= 'PASSWORD'')

DatabaseError:((连接数据库时出错:\ n- SQLCODE: -902 \ n-无法完成对主机"localhost"的网络请求.\ n-无法建立连接.'，-902，335544721)

或

con = fdb.connect(dsn="localhost:C:\Documents\database.db", user='USER' password='PASSWORD'')

DatabaseError:((连接数据库时出错:\ n- SQLCODE: -902 \ n-无法完成对主机"localhost"的网络请求.\ n-无法建立连接.'，-902，335544721)

或

import firebirdsql
con = firebirdsql.connect(host='localhost', database="D:\Documents\database.db", user='USER' password='PASSWORD'')

如果您有任何想法，欢迎您，因为我被困住了.

解决方案

错误表明FDB加载的fbclient.dll不提供Firebird Embedded，并且您的计算机上没有运行Firebird Server.

要解决此问题，您必须:

1. 启动Firebird服务器(通过启动其服务或运行firebird -a)
2. 如果要使用Firebird Embedded而不是Firebird Server，请将FDB指向提供Firebird Embedded的fbclient.dll

第2点可以通过多种方式完成.在我的回答中，我假设使用安装在C:\Program Files\Firebird\Firebird-3.0.5.33220-0_x64中的Firebird 3.从Firebird 3开始，正常的Firebird Server安装也提供了Firebird Embedded.要指向嵌入式Firebird，您可以执行以下操作:

1. 将Firebird安装目录添加到PATH环境变量(确保在之前 %SystemRoot\System32/C:\Windows\System32列出).在正常的Firebird安装中，System32文件夹中安装了没有Firebird Embedded的fbclient.dll，并且如果该文件夹被加载，则不能使用Firebird Embedded.
2. 使用fdb.load_api加载客户端库:

   fdb.load_api('C:/Program Files/Firebird/Firebird-3.0.5.33220-0_x64/fbclient.dll')
   

   这需要在第一次使用fdb.connect之前完成，否则将使用通过常规搜索路径找到的库

3. 使用fb_library_name连接属性指定客户端库:

   con = fdb.connect(dsn='C:/path/to/yourdatabase.fdb', user='sysdba', password='masterkey', 
       fb_library_name='C:/Program Files/Firebird/Firebird-3.0.5.33220-0_x64/fbclient.dll')
   

   需要在使用FDB建立的第一个连接上指定此属性.尽管该属性的存在表明这是每个连接"，但FDB将始终使用加载的第一个客户端库(本质上，它的工作方式就像您在connect之前调用load_api一样).

如果您使用的是Firebird 2.5或更早版本，则需要下载特定的Firebird 2.5 Embedded软件包，并指向其fbembed.dll而不是fbclient.dll.对于Firebird 2.5 Embedded，除非将其fbembed.dll重命名或复制到fbclient.dll，否则无法将其位置添加到路径中.

I can connect to my Firebird database using Firebird ISQL Tool (Firebird 3.0.4) with the following command: connect "C:\Documents\database.db" user 'USER' password 'PASSWORD';

When I want to do it in a Python script (Python v3.7.7 on a Windows10 64 bits), in a virtual environment including fdb v2.0.1 or even firebirdsql v1.1.3, I can't and I systematically get an error.

import fdb
con = fdb.connect(database="C:\Documents\database.db", user='USER' password='PASSWORD'')

DatabaseError: ('Error while connecting to database:\n- SQLCODE: -902\n- Unable to complete network request to host "xnet://Global\FIREBIRD".', -902, 335544721)

or

con = fdb.connect(host='localhost', database="D:\Documents\database.db", user= 'USER' password= 'PASSWORD'')

DatabaseError: ('Error while connecting to database:\n- SQLCODE: -902\n- Unable to complete network request to host "localhost".\n- Failed to establish a connection.', -902, 335544721)

or

con = fdb.connect(dsn="localhost:C:\Documents\database.db", user='USER' password='PASSWORD'')

DatabaseError: ('Error while connecting to database:\n- SQLCODE: -902\n- Unable to complete network request to host "localhost".\n- Failed to establish a connection.', -902, 335544721)

or

import firebirdsql
con = firebirdsql.connect(host='localhost', database="D:\Documents\database.db", user='USER' password='PASSWORD'')

If you have any idea you are welcome as I am stuck.

解决方案

The error indicates that the fbclient.dll loaded by FDB does not provide Firebird Embedded, and that you don't have Firebird Server running on your machine.

To address this you must either:

1. Start Firebird Server (by starting its service or running firebird -a)
2. If you want to use Firebird Embedded instead of Firebird Server, point FDB to a fbclient.dll that provides Firebird Embedded

Point 2 can be done in several ways. In my answer I'm assuming use of Firebird 3 installed in C:\Program Files\Firebird\Firebird-3.0.5.33220-0_x64. Since Firebird 3, a normal Firebird Server install also provides Firebird Embedded. To point to a Firebird Embedded, you can do the following:

1. Add the Firebird installation directory to the PATH environment variable (make sure it is listed before %SystemRoot\System32/C:\Windows\System32). On a normal Firebird installation, the fbclient.dll without Firebird Embedded is installed in the System32 folder, and if that gets loaded, you can't use Firebird Embedded.
2. Use fdb.load_api to load the client library:

   fdb.load_api('C:/Program Files/Firebird/Firebird-3.0.5.33220-0_x64/fbclient.dll')
   

   This needs to be done before the first use of fdb.connect, otherwise the library found through the normal search path will be used

3. Specify the client library using the fb_library_name connection property:

   con = fdb.connect(dsn='C:/path/to/yourdatabase.fdb', user='sysdba', password='masterkey', 
       fb_library_name='C:/Program Files/Firebird/Firebird-3.0.5.33220-0_x64/fbclient.dll')
   

   This property needs to be specified on the first connection made using FDB. Although the existence of the property would suggest this is 'per connection', FDB will always use the first client library loaded (in essence, it works as if you called load_api just before the connect).

If you're using Firebird 2.5 or earlier, you will need to download the specific Firebird 2.5 Embedded package, and point to its fbembed.dll instead of fbclient.dll. For Firebird 2.5 Embedded, adding its location to the path will not work unless you rename or copy its fbembed.dll to fbclient.dll.

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