So, you do not save on the amount of query but save on the amount of logic to handle on the C# side because you do not have to care to delete every details. Looks like I'm stuck deleting each and every entity manually in code. This article will discuss alternative methods for performing cascading deletes using LINQ to SQL. Delete Cascade if foreign keys exists with different delete rule Tom,Q1:----Suppose I have tables t1, t2, t3 and having the relation t1 -> t2 -> t3, where t1 is the root level parent and t3 is the child.Suppose, if there exists a relation between t1 and t2 with delete cascade,t2 and t3 with delete cascade and t1 and t3 with delete restrict.t1 --> See GitHub Issue #21252. The issue was that this whole procedure is done in a transaction (C#, not SQL), which locks the database. ^ So that's where I'm at now. Entity Framework Core (EF Core) represents relationships using foreign keys. Many database systems also offer cascading behaviors that are triggered when an entity is deleted in the database. Introduction. This is called Cascade deleti… From what I gather, it seems that during a transaction like this, as soon as Unable to save changes because a circular dependency was detected in the data to be saved: 'ForeignKey: Profile.InstagramId ... Those tables with a FK should have ON DELETE CASCADE qualifiers. The department will not be set to null. Both result in deleting dependent/child entities when the relationship to their required principal/parent is severed. Here's a super simplified version of my model: User {UserID, Name} Recipe {RecipeID, UserID} Ingredient {IngredientID, UserID} RecipeIngredient {RecipeID, IngredientID} *RecipeIngredient is … There may be different rules for each of the update and delete operations on a single FK constraint. And by a C# transaction, I mean this: ^ This runs on every request/response round from the client to the server (like when the user uploads a files to the point when the data from the file is saved to the database). On a special note, you do not need to have the table having a reference with the On Delete Cascade. The following table shows the result of each OnDelete value on the foreign key constraint created by EF Core migrations or EnsureCreated. For cascade delete, this severing happens because the principal/parent is itself deleted. Record of Table SCARR: Step 1: Go to the TCode:… For example, this code, which is the same as before: Will now result in the following database updates when SaveChanges is called: Likewise, if the relationship is severed using either of the examples from above: Then the posts are updated with null foreign key values when SaveChanges is called: See Changing Foreign Keys and Navigations for more information on how EF Core manages foreign keys and navigations as their values are changed. DA924x said,  you need to alter your database table with DELETE CASCADE, like this: Our application is database first. Th… 2) Delete stored procedure runs to delete old data. Optional relationships have nullable foreign key properties mapped to nullable database columns. is NOT what's supposed to happen if EF has cascading on delete working properly. Yes, ON UPDATE CASCADE will update only the columns used in the FK definition. Similarly, we cannot create INSTEAD OF DELETE trigger on the table when a foreign key CASCADE DELETE rule already exists on the table. Cascade delete means deleting all the dependent record when the primary record gets deleted. Configuring delete behaviors for related entities when a ... (that is, for tracked dependents). I use the [CascadeDelete] attribute like follows in an entity, which successfully adds the "Cascade" delete rule to the Parent-Child relation. We agreed that we would accept a bit of slowness, but not THIS slow. It is also up to the developer to determine how to go about accomplishing the cascading delete. This means there is no longer a cycle in cascading actions, and the database can be created without error on SQL Server. Since data purging mechanisms are typically handled by an asynchronous process (Timer or BPT), performance is not a concern. Do not configure cascade delete in the database when soft-deleting entities. With large files, it will be blocked In the following example, a cascade delete is configured on the relationship between Blog and Post, so the post entity is deleted from the database. But when it comes to altering existing constraints, there is not much you can do. ASP.NET Forums / Data Access / ADO.NET, Entity Framework, LINQ to SQL, NHibernate / Cascade delete entitiyframework core Cascade delete entitiyframework core RSS 1 reply The conflict occurred in database "Scratch", table "dbo.Blogs", column 'OwnerId'. For orphans, the principal/parent entity still exists, but is no longer related to the dependent/child entities. Initially, I thought I could get cascading to work in EF. As per this guide I modeled it with a PersonAddressjoin-table entity, because this way I can store some extra info. See Relationships for more information on modeling relationships. Then I tried allowing EF to automatically cascade deletes: My code shows that the state of the drawing is "modified" after the recommendation is set to deleted. This is an invalid state, and will cause a referential constraint violation in most databases. EF Core covers a closely related concept and implements several different delete behaviors and allows for the configuration of the delete behaviors of individual relationships. EF Core will cascade the delete of the owner so that the blog is also deleted: However, if the blog is not loaded when the owner is deleted: Then an exception will be thrown due to violation of the foreign key constraint in the database: Microsoft.Data.SqlClient.SqlException: The DELETE statement conflicted with the REFERENCE constraint "FK_Blogs_People_OwnerId". In this article, we explored a few examples on DELETE CASCADE and UPDATE CASCADE rules in SQL Server foreign key. See Changing Foreign Keys and Navigations for more information. If the foreign-key does seconds). I would prefer ON CASCADE DELETE just because in my opinion it better describes model and reveals creator's intention. EF will delete a child record(s) (database rows) automatically when its parent is explicitly deleted via the DbContext. The behaviors of ON DELETE NO ACTION and ON DELETE RESTRICT in relational databases are typically either identical or very similar. There is no difference in deleting an entity in the connected and disconnected scenario in EF Core. Given all this, there are a number of approaches we tried. The statement has been terminated. I tell it to delete all records with a foreign key to the record being deleted and then delete the record. This means that it is usually not possible to sever a relationship without loading both sides into the DbContext. Let's understand it with an easy example. There are two options to avoid this referential constraint violation: The first option in only valid for optional relationships where the foreign key property (and the database column to which it is mapped) must be nullable. Before proceeding with the demo, here is summary of the effects for update and delete operations: When a customer gets registered in a table, some of the records also get stored into the dependent table like their purchasesin purchase table. 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: Deleting entities that are no longer associated with any principal/dependent is known as "deleting orphans". Since dependents/children are loaded, they are always deleted by EF Core, and never left for the database to delete. Prior to EF Core it didn't have a name and was not possible to change. When a change is made to a relationship, the related foreign-key property is set to a null value. However, according to the EFCore docs, a Required relationship will be set to Cascade delete functionality. You'll be better off here with writing stored procedure do it manually with T-SQL and calling if from C# code, which is still using the DB engine to do the deletes that is still 10,000 faster than trying to do it from code or using EF. Add ON DELETE CASCADE To Foreign Key Constraint. The Delete value is commonly used when you implement data purging mechanisms, where you need automatic cascade delete between the whole model.. Here the parent table is the table specified in the REFERENCING clause of the definition of an enabled foreign key constraint, and the child table is the table on which the enabled foreign key constraint is defined. The EF Core in-memory database does not currently support cascade deletes in the database. The original approach was like this: The configuration options will likely not make sense if the preceding material is not understood. And letting EF do it is too slow, which you'll find out if you ever try to do it with EF sitting behind a WCF service and watch the service timeout, as example. 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