Delete on cascade update on cascade

CityName varchar 50 ,. Author Recent Posts. Ranga Babu. Latest posts by Ranga Babu see all. Stack Gives Back Featured on Meta. New post summary designs on greatest hits now, everywhere else eventually. Linked 0. Related Hot Network Questions. Question feed. Stack Overflow works best with JavaScript enabled.

Accept all cookies Customize settings. September 12, Spring boot complete tutorial with example 1 Comment. In this article, we will learn about MySQL cascade. We use cascading operation when two tables are dependent on each other. We apply this MySQL cascade on foreign keys. If any data modify from the parent table then this referenced table data will also modify. You can run and debug into all the code in this document by downloading the sample code from GitHub.

BlogId is a foreign key property, the value of which must match the Blog. Id primary key of the blog to which the post belongs. By convention, this relationship is configured as a required, since the Post. BlogId foreign key property is non-nullable. Required relationships are configured to use cascade deletes by default. See Relationships for more information on modeling relationships.

Rather than deleting the blog, we could instead sever the relationship between each post and its blog. This can be done by setting the reference navigation Post. Blog to null for each post:. The relationship can also be severed by removing each post from the Blog. Posts collection navigation:.

In either case the result is the same: the blog is not deleted, but the posts that are no longer associated with any blog are deleted:. Cascade delete and deleting orphans are closely related. EF Core always applies configured cascading behaviors to tracked entities. The exact timing of when cascading behaviors happen to tracked entities can be controlled using ChangeTracker.

CascadeDeleteTiming and ChangeTracker. See Changing Foreign Keys and Navigations for more information. Many database systems also offer cascading behaviors that are triggered when an entity is deleted in the database. For example, using the model above, the following table is created for posts when using SQL Server:.

If we know that the database is configured like this, then we can delete a blog without first loading posts and the database will take care of deleting all the posts that were related to that blog. For example:.