重复SYNCDB会产生不同的结果？

Question

当我运行syncdb它给了我一个MySQL 150错误，可能与FK有关。但是，当我反复运行syncdb时，它最终会工作（下面的整个跟踪）。为什么会发生？

david-MacBook-Pro$ syncdb 
    Creating tables ... 
    Creating table jobs_company 
    Creating table jobs_job 
    Traceback (most recent call last): 
     File "manage.py", line 14, in <module> 
     execute_manager(settings) 
     File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/django/core/management/__init__.py", line 438, in execute_manager 
     utility.execute() 
     File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/django/core/management/__init__.py", line 379, in execute 
     self.fetch_command(subcommand).run_from_argv(self.argv) 
     File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/django/core/management/base.py", line 191, in run_from_argv 
     self.execute(*args, **options.__dict__) 
     File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/django/core/management/base.py", line 220, in execute 
     output = self.handle(*args, **options) 
     File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/django/core/management/base.py", line 351, in handle 
     return self.handle_noargs(**options) 
     File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/django/core/management/commands/syncdb.py", line 101, in handle_noargs 
     cursor.execute(statement) 
     File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/django/db/backends/util.py", line 34, in execute 
     return self.cursor.execute(sql, params) 
     File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/django/db/backends/mysql/base.py", line 86, in execute 
     return self.cursor.execute(query, args) 
     File "build/bdist.macosx-10.6-intel/egg/MySQLdb/cursors.py", line 174, in execute 
     File "build/bdist.macosx-10.6-intel/egg/MySQLdb/connections.py", line 36, in defaulterrorhandler 
    _mysql_exceptions.OperationalError: (1005, "Can't create table 'david542.#sql-2c3_57e' (errno: 150)") 
    david-MacBook-Pro:$ syncdb 
    Creating tables ... 
    Creating table jobs_jobposition 
    Creating table jobs_externaljob 
    Creating table jobs_externalsite 
    Creating table jobs_sitevisit 
    Traceback (most recent call last): 
     File "manage.py", line 14, in <module> 
     execute_manager(settings) 
     File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/django/core/management/__init__.py", line 438, in execute_manager 
     utility.execute() 
     File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/django/core/management/__init__.py", line 379, in execute 
     self.fetch_command(subcommand).run_from_argv(self.argv) 
     File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/django/core/management/base.py", line 191, in run_from_argv 
     self.execute(*args, **options.__dict__) 
     File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/django/core/management/base.py", line 220, in execute 
     output = self.handle(*args, **options) 
     File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/django/core/management/base.py", line 351, in handle 
     return self.handle_noargs(**options) 
     File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/django/core/management/commands/syncdb.py", line 101, in handle_noargs 
     cursor.execute(statement) 
     File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/django/db/backends/util.py", line 34, in execute 
     return self.cursor.execute(sql, params) 
     File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/django/db/backends/mysql/base.py", line 86, in execute 
     return self.cursor.execute(query, args) 
     File "build/bdist.macosx-10.6-intel/egg/MySQLdb/cursors.py", line 174, in execute 
     File "build/bdist.macosx-10.6-intel/egg/MySQLdb/connections.py", line 36, in defaulterrorhandler 
    _mysql_exceptions.OperationalError: (1005, "Can't create table 'david542.#sql-2c3_57f' (errno: 150)") 
    david-MacBook-Pro$ syncdb 
    Creating tables ... 
    Creating table jobs_application 
    Traceback (most recent call last): 
     File "manage.py", line 14, in <module> 
     execute_manager(settings) 
     File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/django/core/management/__init__.py", line 438, in execute_manager 
     utility.execute() 
     File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/django/core/management/__init__.py", line 379, in execute 
     self.fetch_command(subcommand).run_from_argv(self.argv) 
     File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/django/core/management/base.py", line 191, in run_from_argv 
     self.execute(*args, **options.__dict__) 
     File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/django/core/management/base.py", line 220, in execute 
     output = self.handle(*args, **options) 
     File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/django/core/management/base.py", line 351, in handle 
     return self.handle_noargs(**options) 
     File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/django/core/management/commands/syncdb.py", line 101, in handle_noargs 
     cursor.execute(statement) 
     File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/django/db/backends/util.py", line 34, in execute 
     return self.cursor.execute(sql, params) 
     File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/django/db/backends/mysql/base.py", line 86, in execute 
     return self.cursor.execute(query, args) 
     File "build/bdist.macosx-10.6-intel/egg/MySQLdb/cursors.py", line 174, in execute 
     File "build/bdist.macosx-10.6-intel/egg/MySQLdb/connections.py", line 36, in defaulterrorhandler 
    _mysql_exceptions.OperationalError: (1005, "Can't create table 'david542.#sql-2c3_580' (errno: 150)") 
    david-MacBook-Pro$ syncdb 
    Creating tables ... 
    Installing custom SQL ... 
    Installing indexes ... 
    No fixtures found. 

它的工作原理？

Answer 1

它的工作原理是因为FKs没有被创建。分析生成的SQL以验证错误发生的原因，并根据情况重新排序settings.INSTALLED_APPS。