使用south（Django）和MySQL进行模式迁移

Question

我刚看过一个关于django的教程，我遵循了每一步，但每次尝试迁移时都会出现以下错误：

最初的迁移是可行的，但是尝试迁移时，我得到了这样的结果：

  root@debian:/Sites/tumblog# ./manage.py migrate blog

   Traceback (most recent call last):
  File "manage.py", line 11, in <module>
    execute_manager(settings)
  File "/usr/lib/pymodules/python2.6/django/core/management/__init__.py", line 438, in execute_manager
    utility.execute()
  File "/usr/lib/pymodules/python2.6/django/core/management/__init__.py", line 379, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/usr/lib/pymodules/python2.6/django/core/management/base.py", line 191, in run_from_argv
    self.execute(*args, **options.__dict__)
  File "/usr/lib/pymodules/python2.6/django/core/management/base.py", line 220, in execute
    output = self.handle(*args, **options)
  File "/usr/lib/pymodules/python2.6/south/management/commands/migrate.py", line 102, in handle
    delete_ghosts = delete_ghosts,
  File "/usr/lib/pymodules/python2.6/south/migration/__init__.py", line 202, in migrate_app
    success = migrator.migrate_many(target, workplan, database)
  File "/usr/lib/pymodules/python2.6/south/migration/migrators.py", line 215, in migrate_many
    result = migrator.__class__.migrate_many(migrator, target, migrations, database)
  File "/usr/lib/pymodules/python2.6/south/migration/migrators.py", line 284, in migrate_many
    result = self.migrate(migration, database)
  File "/usr/lib/pymodules/python2.6/south/migration/migrators.py", line 121, in migrate
    result = self.run(migration)
  File "/usr/lib/pymodules/python2.6/south/migration/migrators.py", line 95, in run
    return self.run_migration(migration)
  File "/usr/lib/pymodules/python2.6/south/migration/migrators.py", line 77, in run_migration
    migration_function()
  File "/usr/lib/pymodules/python2.6/south/migration/migrators.py", line 56, in <lambda>
    return (lambda: direction(orm))
  File "/Site/tumblog/blog/migrations/0005_initial.py", line 17, in forwards
    ('name', self.gf('django.db.models.fields.CharField')(max_length=255)),
  File "/usr/lib/pymodules/python2.6/south/db/generic.py", line 210, in create_table
    ', '.join([col for col in columns if col]),
  File "/usr/lib/pymodules/python2.6/south/db/generic.py", line 134, in execute
    cursor.execute(sql, params)
  File "/usr/lib/pymodules/python2.6/django/db/backends/util.py", line 15, in execute
    return self.cursor.execute(sql, params)
  File "/usr/lib/pymodules/python2.6/django/db/backends/mysql/base.py", line 86, in execute
    return self.cursor.execute(query, args)
  File "/usr/lib/pymodules/python2.6/MySQLdb/cursors.py", line 166, in execute
    self.errorhandler(self, exc, value)
  File "/usr/lib/pymodules/python2.6/MySQLdb/connections.py", line 35, in defaulterrorhandler
    raise errorclass, errorvalue
_mysql_exceptions.OperationalError: (1050, "Table 'blog_blog' already exists")

我搜索了一下，发现添加--fake可以跳过这个错误，但它不会改变任何事情？这里的问题是什么？我如何解决它？在

Answer 1

你确定加假不会改变什么吗？在

manage.py migrate blog fake

。。。或从mysql控制台手动删除表“blog_blog”；）

Answer 2

问题是迁移尝试创建的表已经存在于数据库中。它们必须是用syncdb创建的（如果您使用了syncdb并在以后开始使用south作为应用程序），或者是通过以前的迁移创建的。在

迁移的名称是0005_initial，这是可疑的。迁移0001-0004在做什么？在

要解决您的问题，您应该首先确保没有重复的迁移（例如，0001_initial创建表，然后0005_initial尝试再次执行此操作）。你只需要为一个应用程序进行一次初始迁移，接下来的迁移应该只记录对架构的更改。在

然后，从数据库中删除表并重新创建它们。类似的方法可能会奏效：

./manage.py migrate [appname]  fake
./manage.py migrate [appname] zero
./manage.py migrate [appname]

如果失败（如果迁移中同时存在现有表和新表，则会失败），那么您必须在mysql控制台中手动删除表。在

Answer 3

你的迁移到底发生了什么？如果您遇到这个错误，那么只要调用create_table两次，因为在初始迁移之前，blog_blog或{}已经存在于您的数据库中（可能是以前尝试创建一个从未迁移到零的blog的剩余部分）。在

如果错误发生在初始迁移完成之前，那么它很可能是一个工件，您只需从数据库中手动删除它，然后再试一次。如果初始迁移成功，但是后面的迁移失败，那么找到blog_blog的重复create_table。在