ubuntu下Django連接mysql數據庫出錯及解決

今天有時間就又開始了Django的學習，下載了《Django Web開發指南》，按照第二章的例子准備做下blog的小例子。沒想到在開始不久在連接數據庫的時候就開始出現了問題。耗費了我一個多小時的時間才終於將它解決。順便說下Django Web開發指南這本書，大致的掃了一下，發現第一章講python基本知識居然有6近0頁，這是雞肋啊。

按照書上的步驟，先創建一個項目

django-admin startproject mysite

之后運行開發服務器，這是一個Django自帶的用於開發期間的服務器

./manage.py runserver

之后創建blog應用

./manage.py startapp blog

然后修改setting.py文件，在INSTALLED_APPS元組的最后加上'mysite.blog',(結尾的逗號是必須的).

之后在models.py中設計model

from django.db import models
class BlogPost(models.Model):
      title = models.CharField(max_length = 150)
      body = models.TextField()
      timestamp = models.DateTimeField()

接下來就是設置數據庫了，也就是我出現問題的地方。Django支持mysql，PostgreSQL，Oracle等數據庫，還有簡單的附帶在python中SQLite.我選用mysql來進行數據庫的設置.

首先是修改setting.py文件，其中的數據庫部分

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.mysql', 
        'NAME': 'mysql',                     
        'USER': 'root',                     
        'PASSWORD': 'fan',                 
        'HOST': 'localhost',                    
        'PORT': '',                    
    }
}

這是最終的配置這個正確的結果，這里的name一定要設定為你的數據庫的名字，如果錯了就會出現一下錯誤信息，我開始寫的是djangodb

    super(Connection, self).__init__(*args, **kwargs2)
_mysql_exceptions.OperationalError: (1049, "Unknown database 'djangodb'")

而一開始我出現的是下面的錯誤，非常的長，而有用的是最后的錯誤提示

root@Fan's PC:/home/fan/djangoProject/mysite# ./manage.py syncdb
Traceback (most recent call last):
  File "./manage.py", line 14, in <module>
    execute_manager(settings)
  File "/usr/lib/pymodules/python2.7/django/core/management/__init__.py", line 438, in execute_manager
    utility.execute()
  File "/usr/lib/pymodules/python2.7/django/core/management/__init__.py", line 379, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/usr/lib/pymodules/python2.7/django/core/management/__init__.py", line 261, in fetch_command
    klass = load_command_class(app_name, subcommand)
  File "/usr/lib/pymodules/python2.7/django/core/management/__init__.py", line 67, in load_command_class
    module = import_module('%s.management.commands.%s' % (app_name, name))
  File "/usr/lib/pymodules/python2.7/django/utils/importlib.py", line 35, in import_module
    __import__(name)
  File "/usr/lib/pymodules/python2.7/django/core/management/commands/syncdb.py", line 7, in <module>
    from django.core.management.sql import custom_sql_for_model, emit_post_sync_signal
  File "/usr/lib/pymodules/python2.7/django/core/management/sql.py", line 6, in <module>
    from django.db import models
  File "/usr/lib/pymodules/python2.7/django/db/__init__.py", line 78, in <module>
    connection = connections[DEFAULT_DB_ALIAS]
  File "/usr/lib/pymodules/python2.7/django/db/utils.py", line 93, in __getitem__
    backend = load_backend(db['ENGINE'])
  File "/usr/lib/pymodules/python2.7/django/db/utils.py", line 33, in load_backend
    return import_module('.base', backend_name)
  File "/usr/lib/pymodules/python2.7/django/utils/importlib.py", line 35, in import_module
    __import__(name)
  File "/usr/lib/pymodules/python2.7/django/db/backends/mysql/base.py", line 14, in <module>
    raise ImproperlyConfigured("Error loading MySQLdb module: %s" % e)
django.core.exceptions.ImproperlyConfigured: Error loading MySQLdb module: No module named MySQLdb
root@Fan's PC:/home/fan/djangoProject/mysite# vi settings.py
root@Fan's PC:/home/fan/djangoProject/mysite# ./manage.py syncdb
Traceback (most recent call last):
  File "./manage.py", line 14, in <module>
    execute_manager(settings)
  File "/usr/lib/pymodules/python2.7/django/core/management/__init__.py", line 438, in execute_manager
    utility.execute()
  File "/usr/lib/pymodules/python2.7/django/core/management/__init__.py", line 379, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/usr/lib/pymodules/python2.7/django/core/management/__init__.py", line 261, in fetch_command
    klass = load_command_class(app_name, subcommand)
  File "/usr/lib/pymodules/python2.7/django/core/management/__init__.py", line 67, in load_command_class
    module = import_module('%s.management.commands.%s' % (app_name, name))
  File "/usr/lib/pymodules/python2.7/django/utils/importlib.py", line 35, in import_module
    __import__(name)
  File "/usr/lib/pymodules/python2.7/django/core/management/commands/syncdb.py", line 7, in <module>
    from django.core.management.sql import custom_sql_for_model, emit_post_sync_signal
  File "/usr/lib/pymodules/python2.7/django/core/management/sql.py", line 6, in <module>
    from django.db import models
  File "/usr/lib/pymodules/python2.7/django/db/__init__.py", line 78, in <module>
    connection = connections[DEFAULT_DB_ALIAS]
  File "/usr/lib/pymodules/python2.7/django/db/utils.py", line 93, in __getitem__
    backend = load_backend(db['ENGINE'])
  File "/usr/lib/pymodules/python2.7/django/db/utils.py", line 33, in load_backend
    return import_module('.base', backend_name)
  File "/usr/lib/pymodules/python2.7/django/utils/importlib.py", line 35, in import_module
    __import__(name)
  File "/usr/lib/pymodules/python2.7/django/db/backends/mysql/base.py", line 14, in <module>
    raise ImproperlyConfigured("Error loading MySQLdb module: %s" % e)
django.core.exceptions.ImproperlyConfigured: Error loading MySQLdb module: No module named MySQLdb

最后的提示是No module named MYSQLdb，就是說沒有和mysql連接上。我開始嘗試進入mysql，不知是為什么，一直出現類似與

error: 'Access denied for user 'root'@'localhost' (using password: NO)'的錯誤。我猜想可能是密碼的原因，不管了，時間緊迫我就想着重新安裝mysql。

在ubuntu下，首先進行卸載，然后安裝，命令如下

卸載
sudo apt-get autoremove --purge mysql-server
sudo apt-get remove mysql-common     //用於徹底刪除
安裝
sudo apt-get install mysql-server
sudo apt-get install mysql-client

在安裝的過程中會彈出一個對話框來設置mysql 的root用戶的密碼。

但是重新安裝好后還是不能成功。查找資料過后發現還需要安裝python-mysql的觸發器，也就是python-mysqldb

apt-get install python-mysqldb

安裝好后，我再進行測試，終於成功了。

root@Fan's PC:/home/fan/djangoProject/mysite# ./manage.py syncdb
Creating tables ...
Creating table auth_permission
Creating table auth_group_permissions
Creating table auth_group
Creating table auth_user_user_permissions
Creating table auth_user_groups
Creating table auth_user
Creating table auth_message
Creating table django_content_type
Creating table django_session
Creating table django_site
Creating table blog_blogpost

You just installed Django's auth system, which means you don't have any superusers defined.
Would you like to create one now? (yes/no): yes
Username (Leave blank to use 'root'): ***
E-mail address: ******@gmail.com
Password: 
Password (again): 
Superuser created successfully.
Installing custom SQL ...
Installing indexes ...
No fixtures found.

總結一下，引發這些問題其實很簡單，就是mysql數據庫和django的配置兩個方面，setting.py文件不能寫錯，另外還需要安裝python-mysqldb，否則會出現錯誤。