django 和 mysql的一次troubleshooting

下面是一次用django连接mysql的经历，记录下来也许以后会有帮助。

首先是用django的./manage.py syncdb 去连接mysql

-bash-3.2$ ./manage.py syncdb
Traceback (most recent call last):
  File "./manage.py", line 10, in <module>
    execute_from_command_line(sys.argv)
  File "/usr/local/lib/python2.7/site-packages/django/core/management/__init__.py", line 399, in execute_from_command_line
    utility.execute()
  File "/usr/local/lib/python2.7/site-packages/django/core/management/__init__.py", line 392, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/usr/local/lib/python2.7/site-packages/django/core/management/base.py", line 242, in run_from_argv
    self.execute(*args, **options.__dict__)
  File "/usr/local/lib/python2.7/site-packages/django/core/management/base.py", line 280, in execute
    translation.activate('en-us')
  File "/usr/local/lib/python2.7/site-packages/django/utils/translation/__init__.py", line 130, in activate
    return _trans.activate(language)
  File "/usr/local/lib/python2.7/site-packages/django/utils/translation/trans_real.py", line 188, in activate
    _active.value = translation(language)
  File "/usr/local/lib/python2.7/site-packages/django/utils/translation/trans_real.py", line 177, in translation
    default_translation = _fetch(settings.LANGUAGE_CODE)
  File "/usr/local/lib/python2.7/site-packages/django/utils/translation/trans_real.py", line 159, in _fetch
    app = import_module(appname)
  File "/usr/local/lib/python2.7/site-packages/django/utils/importlib.py", line 40, in import_module
    __import__(name)
  File "/usr/local/lib/python2.7/site-packages/django/contrib/admin/__init__.py", line 6, in <module>
    from django.contrib.admin.sites import AdminSite, site
  File "/usr/local/lib/python2.7/site-packages/django/contrib/admin/sites.py", line 4, in <module>
    from django.contrib.admin.forms import AdminAuthenticationForm
  File "/usr/local/lib/python2.7/site-packages/django/contrib/admin/forms.py", line 6, in <module>
    from django.contrib.auth.forms import AuthenticationForm
  File "/usr/local/lib/python2.7/site-packages/django/contrib/auth/forms.py", line 17, in <module>
    from django.contrib.auth.models import User
  File "/usr/local/lib/python2.7/site-packages/django/contrib/auth/models.py", line 48, in <module>
    class Permission(models.Model):
  File "/usr/local/lib/python2.7/site-packages/django/db/models/base.py", line 96, in __new__
    new_class.add_to_class('_meta', Options(meta, **kwargs))
  File "/usr/local/lib/python2.7/site-packages/django/db/models/base.py", line 264, in add_to_class
    value.contribute_to_class(cls, name)
  File "/usr/local/lib/python2.7/site-packages/django/db/models/options.py", line 124, in contribute_to_class
    self.db_table = truncate_name(self.db_table, connection.ops.max_name_length())
  File "/usr/local/lib/python2.7/site-packages/django/db/__init__.py", line 34, in __getattr__
    return getattr(connections[DEFAULT_DB_ALIAS], item)
  File "/usr/local/lib/python2.7/site-packages/django/db/utils.py", line 198, in __getitem__
    backend = load_backend(db['ENGINE'])
  File "/usr/local/lib/python2.7/site-packages/django/db/utils.py", line 113, in load_backend
    return import_module('%s.base' % backend_name)
  File "/usr/local/lib/python2.7/site-packages/django/utils/importlib.py", line 40, in import_module
    __import__(name)
  File "/usr/local/lib/python2.7/site-packages/django/db/backends/mysql/base.py", line 17, in <module>
    raise ImproperlyConfigured("Error loading MySQLdb module: %s" % e)
django.core.exceptions.ImproperlyConfigured: Error loading MySQLdb module: No module named MySQLdb

这里面最重要的就是最后一句 No module named MySQLdb. 这说明MySQL-python这个package没有安装成功。于是用pip2.7 install MySQL-python来安装，但是遇到如下错误。

[root@kramer site-packages]# pip2.7 install MySQL-python
Downloading/unpacking MySQL-python
  Downloading MySQL-python-1.2.5.zip (108kB): 108kB downloaded
  Running setup.py (path:/tmp/pip_build_root/MySQL-python/setup.py) egg_info for package MySQL-python

Installing collected packages: MySQL-python
  Running setup.py install for MySQL-python
    building '_mysql' extension
    gcc -pthread -fno-strict-aliasing -g -O2 -DNDEBUG -g -fwrapv -O3 -Wall -Wstrict-prototypes -fPIC -Dversion_info=(1,2,5,'final',1) -D__version__=1.2.5 -I/usr/include/mysql -I/usr/local/include/python2.7 -c _mysql.c -o build/temp.linux-x86_64-2.7/_mysql.o -g -pipe -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector --param=ssp-buffer-size=4 -m64 -D_GNU_SOURCE -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE -fno-strict-aliasing -fwrapv
    _mysql.c:44:23: error: my_config.h: No such file or directory
    _mysql.c:46:19: error: mysql.h: No such file or directory
    _mysql.c:47:26: error: mysqld_error.h: No such file or directory
    _mysql.c:48:20: error: errmsg.h: No such file or directory

这个错误很长所以只截取一小段来看。发现都是c/c++的头文件找不到，这一般是因为某个dev的包没有找到。在linux上你安装一个软件的时候这个软件通常有两部分，一个是dev包一个是应用包。如果你只要使用的话安装应用包就可以了，但是某些情况下需要dev包。 这里是mysql的一些头文件找不到所以我们应该安装mysql的dev包。 猜测名字应该是类似于mysql-devel

[root@kramer site-packages]# yum install mysql-devel
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
 * base: mirror.tocici.com
 * extras: mirror.tocici.com
 * updates: mirror.tocici.com
Setting up Install Process
Resolving Dependencies
--> Running transaction check
---> Package mysql-devel.i386 0:5.0.95-5.el5_9 set to be updated
---> Package mysql-devel.x86_64 0:5.0.95-5.el5_9 set to be updated
--> Finished Dependency Resolution

Dependencies Resolved

========================================================================================================================================================================
 Package                                   Arch                                 Version                                        Repository                          Size
========================================================================================================================================================================
Installing:
 mysql-devel                               i386                                 5.0.95-5.el5_9                                 base                               2.4 M
 mysql-devel                               x86_64                               5.0.95-5.el5_9                                 base                               2.5 M

Transaction Summary
========================================================================================================================================================================
Install       2 Package(s)
Upgrade       0 Package(s)

Total download size: 4.9 M
Is this ok [y/N]: y
Downloading Packages:
(1/2): mysql-devel-5.0.95-5.el5_9.i386.rpm                                                                                                       | 2.4 MB     00:00
(2/2): mysql-devel-5.0.95-5.el5_9.x86_64.rpm                                                                                                     | 2.5 MB     00:00
------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Total                                                                                                                                   6.5 MB/s | 4.9 MB     00:00
Running rpm_check_debug
Running Transaction Test
Finished Transaction Test
Transaction Test Succeeded
Running Transaction
  Installing     : mysql-devel                                                                                                                                      1/2
  Installing     : mysql-devel                                                                                                                                      2/2

Installed:
  mysql-devel.i386 0:5.0.95-5.el5_9                                                 mysql-devel.x86_64 0:5.0.95-5.el5_9

Complete!

果然有这么一个包。安装之后就可以执行pip install。