Using a database to delete fields and models of Django

Source: Internet
Author: User
This article mainly introduces how to delete fields and models in Django through databases. Suppose we have created a data model named book. For more information, see Delete field

Deleting a field from the Model is much easier than adding it. To delete a field, follow these steps:

  • Delete the field and restart your web server.
  • Run the following command to delete fields from the database:

Alter table books_book drop column num_pages;

Ensure that the operation order is correct. If you delete a field from the database, Django immediately throws an exception.
Delete multiple-to-multiple Association fields

Because many-to-many correlated fields are different from common fields, the delete operation is different.

  • Delete ManyToManyField from your model and restart the web server.
  • Run the following command to delete an associated table from a database:

Drop table books_book_authors;

Pay attention to the operation sequence as above.
Delete model

Deleting the entire model is easier than deleting a field. To delete a model, follow these steps:

  • Delete the model you want to delete from the file, and restart the web server models. py.
  • Run the following command to delete a table from the database:

Drop table books_book;

  • When you need to delete any dependent tables from the database (that is, any tables that have foreign keys with the books_book table ).

As in the previous section, you must do it in this order.

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