我对模型进行了一些更改，然后运行了
python manage.py makemigrations python manage.py migrate
我得到了这个追溯：
Operations to perform:
Synchronize unmigrated apps: staticfiles, messages
Apply all migrations: sessions, admin, study, auth, quiz, contenttypes, main
Synchronizing apps without migrations:
Creating tables...
Running deferred SQL...
Installing custom SQL...
Running migrations:
Rendering model states... DONE
Applying quiz.0013_auto_20151005_0644...Traceback (most recent call last):
File "manage.py", line 10, in <module>
execute_from_command_line(sys.argv)
File "/usr/local/lib/python2.7/dist-packages/django/core/management/__init__.py", line 338, in execute_from_command_line
utility.execute()
File "/usr/local/lib/python2.7/dist-packages/django/core/management/__init__.py", line 330, in execute
self.fetch_command(subcommand).run_from_argv(self.argv)
File "/usr/local/lib/python2.7/dist-packages/django/core/management/base.py", line 393, in run_from_argv
self.execute(*args, **cmd_options)
File "/usr/local/lib/python2.7/dist-packages/django/core/management/base.py", line 444, in execute
output = self.handle(*args, **options)
File "/usr/local/lib/python2.7/dist-packages/django/core/management/commands/migrate.py", line 222, in handle
executor.migrate(targets, plan, fake=fake, fake_initial=fake_initial)
File "/usr/local/lib/python2.7/dist-packages/django/db/migrations/executor.py", line 110, in migrate
self.apply_migration(states[migration], migration, fake=fake, fake_initial=fake_initial)
File "/usr/local/lib/python2.7/dist-packages/django/db/migrations/executor.py", line 154, in apply_migration
self.recorder.record_applied(migration.app_label, migration.name)
File "/usr/local/lib/python2.7/dist-packages/django/db/migrations/recorder.py", line 67, in record_applied
self.migration_qs.create(app=app, name=name)
File "/usr/local/lib/python2.7/dist-packages/django/db/models/query.py", line 348, in create
obj.save(force_insert=True, using=self.db)
File "/usr/local/lib/python2.7/dist-packages/django/db/models/base.py", line 734, in save
force_update=force_update, update_fields=update_fields)
File "/usr/local/lib/python2.7/dist-packages/django/db/models/base.py", line 762, in save_base
updated = self._save_table(raw, cls, force_insert, force_update, using, update_fields)
File "/usr/local/lib/python2.7/dist-packages/django/db/models/base.py", line 846, in _save_table
result = self._do_insert(cls._base_manager, using, fields, update_pk, raw)
File "/usr/local/lib/python2.7/dist-packages/django/db/models/base.py", line 885, in _do_insert
using=using, raw=raw)
File "/usr/local/lib/python2.7/dist-packages/django/db/models/manager.py", line 127, in manager_method
return getattr(self.get_queryset(), name)(*args, **kwargs)
File "/usr/local/lib/python2.7/dist-packages/django/db/models/query.py", line 920, in _insert
return query.get_compiler(using=using).execute_sql(return_id)
File "/usr/local/lib/python2.7/dist-packages/django/db/models/sql/compiler.py", line 974, in execute_sql
cursor.execute(sql, params)
File "/usr/local/lib/python2.7/dist-packages/django/db/backends/utils.py", line 79, in execute
return super(CursorDebugWrapper, self).execute(sql, params)
File "/usr/local/lib/python2.7/dist-packages/django/db/backends/utils.py", line 64, in execute
return self.cursor.execute(sql, params)
File "/usr/local/lib/python2.7/dist-packages/django/db/utils.py", line 97, in __exit__
six.reraise(dj_exc_type, dj_exc_value, traceback)
File "/usr/local/lib/python2.7/dist-packages/django/db/backends/utils.py", line 64, in execute
return self.cursor.execute(sql, params)
django.db.utils.IntegrityError: duplicate key value violates unique constraint "django_migrations_pkey"
DETAIL: Key (id)=(27) already exists.
我不太清楚如何解释主键已经存在的错误。奇怪的是，它将字段添加到数据库中，因为我在我的网站上看到它输出，当我运行shell时，我可以看到字段已添加，并且填充了“我选择的”默认数据。
我决定再次运行迁移，看看它是否会在第二次传递之后再次进行跟踪...
Operations to perform:
Synchronize unmigrated apps: staticfiles, messages
Apply all migrations: sessions, admin, study, auth, quiz, contenttypes, main
Synchronizing apps without migrations:
Creating tables...
Running deferred SQL...
Installing custom SQL...
Running migrations:
Rendering model states... DONE
Applying quiz.0013_auto_20151005_0644...Traceback (most recent call last):
File "manage.py", line 10, in <module>
execute_from_command_line(sys.argv)
File "/usr/local/lib/python2.7/dist-packages/django/core/management/__init__.py", line 338, in execute_from_command_line
utility.execute()
File "/usr/local/lib/python2.7/dist-packages/django/core/management/__init__.py", line 330, in execute
self.fetch_command(subcommand).run_from_argv(self.argv)
File "/usr/local/lib/python2.7/dist-packages/django/core/management/base.py", line 393, in run_from_argv
self.execute(*args, **cmd_options)
File "/usr/local/lib/python2.7/dist-packages/django/core/management/base.py", line 444, in execute
output = self.handle(*args, **options)
File "/usr/local/lib/python2.7/dist-packages/django/core/management/commands/migrate.py", line 222, in handle
executor.migrate(targets, plan, fake=fake, fake_initial=fake_initial)
File "/usr/local/lib/python2.7/dist-packages/django/db/migrations/executor.py", line 110, in migrate
self.apply_migration(states[migration], migration, fake=fake, fake_initial=fake_initial)
File "/usr/local/lib/python2.7/dist-packages/django/db/migrations/executor.py", line 148, in apply_migration
state = migration.apply(state, schema_editor)
File "/usr/local/lib/python2.7/dist-packages/django/db/migrations/migration.py", line 115, in apply
operation.database_forwards(self.app_label, schema_editor, old_state, project_state)
File "/usr/local/lib/python2.7/dist-packages/django/db/migrations/operations/fields.py", line 62, in database_forwards
field,
File "/usr/local/lib/python2.7/dist-packages/django/db/backends/base/schema.py", line 398, in add_field
self.execute(sql, params)
File "/usr/local/lib/python2.7/dist-packages/django/db/backends/base/schema.py", line 111, in execute
cursor.execute(sql, params)
File "/usr/local/lib/python2.7/dist-packages/django/db/backends/utils.py", line 79, in execute
return super(CursorDebugWrapper, self).execute(sql, params)
File "/usr/local/lib/python2.7/dist-packages/django/db/backends/utils.py", line 64, in execute
return self.cursor.execute(sql, params)
File "/usr/local/lib/python2.7/dist-packages/django/db/utils.py", line 97, in __exit__
six.reraise(dj_exc_type, dj_exc_value, traceback)
File "/usr/local/lib/python2.7/dist-packages/django/db/backends/utils.py", line 64, in execute
return self.cursor.execute(sql, params)
django.db.utils.ProgrammingError: column "lang1_back_to_choice" of relation "quiz_langpairinstructions" already exists
现在，如果我再试一次，我将永远得到第二次追溯。我想知道我该怎么做，所以我可以在未来进行迁移。如果数据库本身看起来一切顺利，为什么我会收到此错误？
答案 0 :(得分：19)
还有另一种方式。既然您知道id表中的最后一个django_migrations值，那就说它是100.然后，您需要这样做：
ALTER SEQUENCE django_migrations_id_seq RESTART WITH 101;
答案 1 :(得分：6)
我忽略了＆＃39; django_migrations_pkey＆＃39;专栏，我没有意识到这是在数据库中。不知何故，django落后于实际的数据库，并试图使用主键（pk = 27）而不是它实际上的数字（应该是28）
我不确定如何从django中更改此内容，所以我只是删除了数据库中的最后一列，因此它是一个主键更短，并且正在使用django并且它开始正常工作。
答案 2 :(得分：3)
在我之前手动修改django迁移表条目之后（在添加了一些先前狡猾的迁移然后删除之后），我收到了此错误。
这使得django_migrations ID与django_migrations表中条目的默认位置无关（可以这么说）。
问题是django获取最后一个条目的ID而+1来创建一个新条目（在下表中：197 + 1 = 198），但是你可以看到Key（id）=（198）已经存在在表中。
187 | foo_app | 0016_auto_20161220_2332 | 2017-01-06 05:22:07.666172+00
198 | bar_app | 0004_auto_20160423_2122 | 2017-01-13 05:38:31.922738+00
197 | baz_app | 0013_auto_20170203_2311 | 2017-02-08 18:50:22.70143+00
正如您所看到的，左侧主键的编号无序。 我所做的是手动删除django_migration中的无序条目，然后重新添加它们。
DELETE from django_migrations where name = '0004_auto_20160423_2122';
DELETE from django_migrations where name = '0013_auto_20170203_2311';
INSERT INTO django_migrations VALUES (188, 'baz_app', '0013_auto_20170203_2311', date());
INSERT INTO django_migrations VALUES (189, 'bar_app', '0004_auto_20160423_2122', date());
另外值得注意的是，我最初尝试添加的迁移＆＃39; new_app，＆＃39; 0002_auto_00000000_1111＆＃39;实际上修改了postgres中的new_app表，但是django_migrations表没有更新。
所以我第二次尝试重新运行迁移0002_auto_00000000_1111我收到了错误：
django.db.utils.ProgrammingError: column "new_app_field" of relation "new_app_new" already exists
上面我的解决方案为我解决了这个问题。
答案 3 :(得分：0)
只需为django_migrations表重新编制索引就对我有用。