Consider this simple model where Blog is the principal/parent in a relationship with Post, which is the dependent/child. This is bad when we have clients trying to view their reports (which is what the API does). This means there is no longer a cycle in cascading actions, and the database can be created without error on SQL Server. If you want to add an on delete cascade to an existing foreign key constraint, you are going to need two statements.. Syntax. but when I delete my Service the data in table Lexikon will still be in it. But if anyone has any alternative suggestion, I'm all ears. 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. It is now known as ClientSetNull as described in the next section. to be much quicker than doing manual deletions for every single entity (most likely not as fast as the stored procedure but hopefully faster than manual deletions through-and-through). I don't think you will see a performance difference between trigger and using cascade. I'm still not able to get cascading to work in EF and so deleting all the Specify foreign key for the details tables which references to the primary key of master and set Delete rule = Cascade . Make sure to fully understand these concepts before tackling the material here. Looks like I'm stuck deleting each and every entity manually in code. Consider an example of Customer Registration. The alter table command lets you do quite a bit. An entity with a foreign key is the child or dependent entity in the relationship. For example: SaveChanges generates the following SQL, using SQL Server as an example: Rather than deleting the blog, we could instead sever the relationship between each post and its blog. 3) File is parsed and new data is made into new entities. 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 --> EF Core always applies configured cascading behaviors to tracked entities. Cascading deletes are needed when a dependent/child entity can no longer be associated with its current principal/parent. Before proceeding with the demo, here is summary of the effects for update and delete operations: This means that if the application loads all relevant dependent/child entities into the DbContext, as is shown in the examples above, then cascading behaviors will be correctly applied regardless of how the database is configured. 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 only values that will cause cascading behaviors on the database are Cascade and SetNull. Unfortunately I'm not familiar with the OnDelete-Method so I … Cascading doesn't work because for all the objects I'd like to cascade upon deletion, there will be multiple or cyclical cascade paths which is not allowed (for some bizarre reason) in SQL Server. The statement has been terminated. 2) Delete stored procedure runs to delete old data. On a special note, you do not need to have the table having a reference with the On Delete Cascade. ADO.NET Entity Framework and LINQ to Entities, If you use entity framework database first, As. Cascading delete refers to the action of removing records associated by a foreign key relationship to a record that is the target of a deletion action. I was afraid someone might say that. Cascading doesn't work because for all the objects I'd like to cascade upon deletion, there will be multiple or cyclical cascade paths which is not allowed (for some bizarre reason) in SQL Server. "Delete" Example. The following example shows how to setup and cascade works when deleting record from parent table. Well, neither ON DELETE CASCADE nor INSTEAD OF DELETE work. SaveChanges in this case will delete just the blog, since that's the only entity being tracked: This would result in an exception if the foreign key constraint in the database is not configured for cascade deletes. On the other hand when I delete the lexikon it will automatically delete the Service which is nice but I also want it to be happen to my Lexikon when I delete my Service. With large files, it will be blocked Name the project Notes and, to speed things up, check Use Core Dataat the bottom. See Changing Foreign Keys and Navigations for more information. 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. If delete rule for Department.employees is also nullify, then when you delete the department, its employees are not let go. In my previous post oData Service – with INSERT statement, we have already discussed about how to INSERT record into table using GET_ENTITY method. This one for example: In other words: Do all the parsing of the file first, THEN run the delete stored procedure and save. 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