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首页 / 【干货攻略】Python封装DM达梦数据库操作

【干货攻略】Python封装DM达梦数据库操作

达梦E学 2021-07-19
7415


dmPython是DM数据库的Python接口，使用dmPython可以实现Python应用程序对达梦数据库的访问和操作。本文将介绍Python封装DM达梦数据库的操作方法。

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 ✦ 一、测试环境 ✦ 


1.操作系统版本
    [root@dm8 dmPython]# cat etc/redhat-release
    Red Hat Enterprise Linux Server release 7.5 (Maipo)
    [root@dm8 dmPython]#

    2、达梦数据库版本：

      [root@dm8 dmPython]# disql SYSDBA/SYSDBA
      服务器[LOCALHOST:5236]:处于普通打开状态
      登录使用时间: 7.944(毫秒)
      disql V8
      SQL> select * from v$version;
       
      行号     BANNER                   
      ---------- -------------------------
      1          DM Database Server 64 V8
      2          DB Version: 0x7000a
       
      已用时间: 1.862(毫秒). 执行号:3186.
      SQL>

      注意这里的DM8 是测试版，所以版本和官方下载的不一样。


      ☆ 二、安装dmPython ☆


      Python 有现成的mysql，oracle 等数据库包，可以直接import 使用，但对于达梦数据库，必须首先安装dmPython，才可以使用。

      在$DM_HOME/drivers 目录下有多种类型的驱动：

        [dmdba@dm8 ~]$ cd dm/dmdbms/drivers/
        [dmdba@dm8 drivers]$ ls
        dci  dpi  jdbc  node.js  oci  odbc  php_pdo  python
        [dmdba@dm8 drivers]$
        [dmdba@dm8 drivers]$ cd python/
        [dmdba@dm8 python]$ ls
        dmPython  third
        [dmdba@dm8 python]$ cd dmPython/
        [dmdba@dm8 dmPython]$ ls
        Buffer.c      dmPython.vcxproj          Error.c    exObject.c   row.c     tObject.c  var_pub.h    vInterval.c  vObject.c
        Buffer.h      dmPython.vcxproj.filters  Error.h    py_Dameng.c  row.h     trc.c      vBfile.c     vLob.c       vString.c
        Connection.c  dmPython.vcxproj.user     exBfile.c  py_Dameng.h  setup.py  trc.h      vCursor.c    vlong.c
        Cursor.c      Environment.c             exLob.c    README.txt   strct.h   var.c      vDateTime.c  vNumber.c
        [dmdba@dm8 dmPython]$

        这里我们需要手工安装dmPython 包。进入dmPython目录后执行命令：

          python setup.py install

          命令虽简单，但过程插曲比较多。

          1、插曲一：权限问题Permission denied

          开始使用dmdba 用户执行，报如下错误：

            [dmdba@dm8 dmPython]$ python setup.py install
            running install
            error: can't create or remove files in install directory
             
            The following error occurred while trying to add or remove files in the
            installation directory:
             
                [Errno 13] Permission denied: '/usr/lib64/python2.7/site-packages/test-easy-install-3032.write-test'
             
            The installation directory you specified (via --install-dir, --prefix, or
            the distutils default setting) was:
             
                usr/lib64/python2.7/site-packages/
             
            Perhaps your account does not have write access to this directory?  If the
            installation directory is a system-owned directory, you may need to sign in
            as the administrator or "root" account.  If you do not have administrative
            access to this machine, you may wish to choose a different installation
            directory, preferably one that is listed in your PYTHONPATH environment
            variable.
             
            For information on other options, you may wish to consult the
            documentation at:
             
              https://pythonhosted.org/setuptools/easy_install.html
             
            Please make the appropriate changes for your system and try again.
             
            [dmdba@dm8 dmPython]$

            根据提示，需要使用root用户来安装dmPython。


            2、 插曲二: cannot locate an Dameng software installation

            切换成root用户执行，又报如下错误：

              [root@dm8 ~]# cd dm/dmdbms/drivers/python/dmPython
              [root@dm8 dmPython]# python setup.py install
              Traceback (most recent call last):
                File "setup.py", line 103, in <module>
                  raise DistutilsSetupError("cannot locate an Dameng software " 
              distutils.errors.DistutilsSetupError: cannot locate an Dameng software installation
              [root@dm8 dmPython]#

              因为安装依赖DM的环境，这里在root用户下配置dm的环境变量。

                [root@dm8 dmPython]# cat ~/.bash_profile
                # .bash_profile
                 
                # Get the aliases and functions
                if [ -f ~/.bashrc ]; then
                    . ~/.bashrc
                fi
                 
                # User specific environment and startup programs
                 
                PATH=$PATH:$HOME/bin
                 
                export PATH
                 
                export PATH="/dm/dmdbms/bin:$PATH"
                 
                export LD_LIBRARY_PATH="$LD_LIBRARY_PATH:/dm/dmdbms/bin"
                export DM_HOME="/dm/dmdbms"
                [root@dm8 dmPython]#


                3 、插曲三：unable to execute gcc: No such file or directory

                解决上面的问题后继续安装：

                  [root@dm8 dmPython]# source ~/.bash_profile
                  [root@dm8 dmPython]# python setup.py  install
                  running install
                  running bdist_egg
                  running egg_info
                  creating dmPython.egg-info
                  writing dmPython.egg-info/PKG-INFO
                  writing top-level names to dmPython.egg-info/top_level.txt
                  writing dependency_links to dmPython.egg-info/dependency_links.txt
                  writing manifest file 'dmPython.egg-info/SOURCES.txt'
                  reading manifest file 'dmPython.egg-info/SOURCES.txt'
                  writing manifest file 'dmPython.egg-info/SOURCES.txt'
                  installing library code to build/bdist.linux-x86_64/egg
                  running install_lib
                  running build_ext
                  building 'dmPython' extension
                  creating build
                  creating build/temp.linux-x86_64-2.7
                  gcc -pthread -fno-strict-aliasing -O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -m64 -mtune=generic -D_GNU_SOURCE -fPIC -fwrapv -DNDEBUG -O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -m64 -mtune=generic -D_GNU_SOURCE -fPIC -fwrapv -fPIC -DDM64 -I/dm/dmdbms/include -I/usr/include/python2.7 -c py_Dameng.c -o build/temp.linux-x86_64-2.7/py_Dameng.o -DBUILD_VERSION=2.3
                  unable to execute gcc: No such file or directory
                  error: command 'gcc' failed with exit status 1
                  [root@dm8 dmPython]#

                  提示缺少gcc 包，直接yum 安装：

                    [root@dm8 dmPython]# yum install gcc* -y


                    4、插曲四：py_Dameng.h:8:20: fatal error: Python.h: No such file or directory

                    解决gcc 包之后继续安装：

                      [root@dm8 dmPython]# python setup.py  install
                      running install
                      running bdist_egg
                      running egg_info
                      writing dmPython.egg-info/PKG-INFO
                      writing top-level names to dmPython.egg-info/top_level.txt
                      writing dependency_links to dmPython.egg-info/dependency_links.txt
                      reading manifest file 'dmPython.egg-info/SOURCES.txt'
                      writing manifest file 'dmPython.egg-info/SOURCES.txt'
                      installing library code to build/bdist.linux-x86_64/egg
                      running install_lib
                      running build_ext
                      building 'dmPython' extension
                      gcc -pthread -fno-strict-aliasing -O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -m64 -mtune=generic -D_GNU_SOURCE -fPIC -fwrapv -DNDEBUG -O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -m64 -mtune=generic -D_GNU_SOURCE -fPIC -fwrapv -fPIC -DDM64 -I/dm/dmdbms/include -I/usr/include/python2.7 -c py_Dameng.c -o build/temp.linux-x86_64-2.7/py_Dameng.o -DBUILD_VERSION=2.3
                      In file included from py_Dameng.c:3:0:
                      py_Dameng.h:8:20: fatal error: Python.h: No such file or directory
                       #include <Python.h>
                                          ^
                      compilation terminated.
                      error: command 'gcc' failed with exit status 1
                      [root@dm8 dmPython]#

                      这里提示：

                        py_Dameng.h:8:20: fatal error: Python.h: No such file or directory

                        这里是缺少python-devel 包，老方法，直接yum 解决：

                          [root@dm8 dmPython]# yum install python-devel

                          最后终于安装成功：

                            [root@dm8 dmPython]# python setup.py install
                            ……
                            creating dist
                            creating 'dist/dmPython-2.3-py2.7-linux-x86_64.egg' and adding 'build/bdist.linux-x86_64/egg' to it
                            removing 'build/bdist.linux-x86_64/egg' (and everything under it)
                            Processing dmPython-2.3-py2.7-linux-x86_64.egg
                            Copying dmPython-2.3-py2.7-linux-x86_64.egg to usr/lib64/python2.7/site-packages
                            Adding dmPython 2.3 to easy-install.pth file
                             
                            Installed usr/lib64/python2.7/site-packages/dmPython-2.3-py2.7-linux-x86_64.egg
                            Processing dependencies for dmPython==2.3
                            Finished processing dependencies for dmPython==2.3
                            [root@dm8 dmPython]#


                            ☆ 三、测试dmPython ☆

                              [root@dm8 dmPython]# python
                              Python 2.7.5 (default, Feb 20 2018, 09:19:12) 
                              [GCC 4.8.5 20150623 (Red Hat 4.8.5-28)] on linux2
                              Type "help", "copyright", "credits" or "license" for more information.
                              >>> import dmPython
                              /usr/lib64/python2.7/site-packages/dmPython-2.3-py2.7-linux-x86_64.egg/dmPython.py:3: UserWarning: Module dmPython was already imported from /usr/lib64/python2.7/site-packages/dmPython-2.3-py2.7-linux-x86_64.egg/dmPython.pyc, but /dm/dmdbms/drivers/python/dmPython is being added to sys.path
                              >>> conn=dmPython.connect(user='SYSDBA',password='SYSDBA',server='192.168.20.171',port=5236)
                              >>> cursor=conn.cursor()
                              >>> cursor.execute("select 'https://www.cndba.cn' from dual")
                              <__builtin__.DmdbCursor on <dmPython.Connection to SYSDBA@192.168.20.171:5236>>
                              >>> rets=cursor.fetchall()
                              >>> rets
                              [('https://www.cndba.cn',)]
                              >>> cursor.close()
                              >>> conn.close()

                              此时通过dmPython 访问DM 数据库正常，dmPython 接口更多的详细说明可直接参考达梦数据库官方文档《DM8_dmPython 使用手册》。

                              好，以上是本次分享内容，希望能给大家带来帮助。

                              PS：本文首次发表于https://www.cndba.cn/cndba/dave/article/3827，经作者本人同意后在本公众号分享。

                              往期回顾

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