django如何重新生成表(django创建表)

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在网上看到都是使用Django的models和makemigration，migrate命令来创建新表，并使用。可是我的数据已经存在了已经创建好，并且已经存储有数据了，不能再重新创建新表了。了解Django的表明和models名称的映射关系就可以让Django使用已经存在的表。

假如在Django存在models如下：

[python]?viewplain?copy

from?django.db?import?models

#?Create?your?models?here.

class?Sciencenews(models.Model):

id?=?models.CharField(max_length=36,primary_key=True)

first_module?=?models.CharField(max_length=30,default="News")

second_module?=?models.CharField(max_length=30,default="Latest?News")

title?=?models.CharField(max_length=300)

author?=?models.CharField(max_length=60,null=True)

publish_date?=?models.CharField(max_length=35,null=True)

content?=?models.TextField(null=True)

crawl_date?=?models.CharField(max_length=35,null=True)

from_url?=?models.CharField(max_length=350,null=True)

执行数据迁移命令：

[python]?viewplain?copy

python?manage.py?makemigration

python?manage.py?migrate

会在数据库中生成名称为show_sciencenews的数据表。show为应用名称，此处我的应用名称为show。可以看到Django创建表的命名规则：应用名_模型名。

我的存储爬取到的数据的表格名称原来为science_news,想要Django使用它，而不是创建新的表，只需要把的它的名称改为：应用名_要与该表映射的models名称，在此处我改为show_sciencenews。然后使用如上的数据迁移命令，这时可能会提示数据表已经存在的错误，不用理会，models已经和数据表映射上了。接下来只需要正常使用models和数据表就可以了。

;

django创建数据库表方法如下：

catcher:mysite?catcher$?python?manage.py?makemigrations?books

Migrations?for?'books':

??0001_initial.py:

????-?Create?model?Author

????-?Create?model?Book

????-?Create?model?Publisher

????-?Add?field?publisher?to?book

catcher:mysite?catcher$?python?manage.py?sqlmigrate?books?0001

BEGIN;

--

--?Create?model?Author

--

CREATE?TABLE?"books_author"?("id"?integer?NOT?NULL?PRIMARY?KEY?AUTOINCREMENT,?"first_name"?varchar(30)?NOT?NULL,?"last_name"?varchar(40)?NOT?NULL,?"email"?varchar(254)?NOT?NULL);

--

--?Create?model?Book

--

CREATE?TABLE?"books_book"?("id"?integer?NOT?NULL?PRIMARY?KEY?AUTOINCREMENT,?"title"?varchar(100)?NOT?NULL,?"publication_date"?date?NOT?NULL);

CREATE?TABLE?"books_book_authors"?("id"?integer?NOT?NULL?PRIMARY?KEY?AUTOINCREMENT,?"book_id"?integer?NOT?NULL?REFERENCES?"books_book"?("id"),?"author_id"?integer?NOT?NULL?REFERENCES?"books_author"?("id"));

--

--?Create?model?Publisher

--

CREATE?TABLE?"books_publisher"?("id"?integer?NOT?NULL?PRIMARY?KEY?AUTOINCREMENT,?"name"?varchar(30)?NOT?NULL,?"address"?varchar(50)?NOT?NULL,?"city"?varchar(60)?NOT?NULL,?"state_province"?varchar(30)?NOT?NULL,?"country"?varchar(50)?NOT?NULL,?"website"?varchar(200)?NOT?NULL);

--

--?Add?field?publisher?to?book

--

ALTER?TABLE?"books_book"?RENAME?TO?"books_book__old";

CREATE?TABLE?"books_book"?("id"?integer?NOT?NULL?PRIMARY?KEY?AUTOINCREMENT,?"title"?varchar(100)?NOT?NULL,?"publication_date"?date?NOT?NULL,?"publisher_id"?integer?NOT?NULL?REFERENCES?"books_publisher"?("id"));

INSERT?INTO?"books_book"?("publication_date",?"publisher_id",?"id",?"title")?SELECT?"publication_date",?NULL,?"id",?"title"?FROM?"books_book__old";

DROP?TABLE?"books_book__old";

CREATE?INDEX?"books_book_2604cbea"?ON?"books_book"?("publisher_id");

?

COMMIT;

catcher:mysite?catcher$

???

?

catcher:mysite?catcher$?sudo?python?manage.py?migratePassword:Operations?to?perform:??Apply?all?migrations:?admin,?contenttypes,?books,?auth,?sessionsRunning?migrations:??Rendering?model?states...?DONE??Applying?contenttypes.0001_initial...?OK??Applying?auth.0001_initial...?OK??Applying?admin.0001_initial...?OK??Applying?admin.0002_logentry_remove_auto_add...?OK??Applying?contenttypes.0002_remove_content_type_name...?OK??Applying?auth.0002_alter_permission_name_max_length...?OK??Applying?auth.0003_alter_user_email_max_length...?OK??Applying?auth.0004_alter_user_username_opts...?OK??Applying?auth.0005_alter_user_last_login_null...?OK??Applying?auth.0006_require_contenttypes_0002...?OK??Applying?auth.0007_alter_validators_add_error_messages...?OK??Applying?books.0001_initial...?OK??Applying?sessions.0001_initial...?OKcatcher:mysite?catcher$