Cannot Delete or Update a Parent Row: a Foreign Key Constraint Fails

Cannot delete or update a parent row: a foreign key constraint fails

As is, you must delete the row out of the advertisers table before you can delete the row in the jobs table that it references. This:

ALTER TABLE `advertisers`
  ADD CONSTRAINT `advertisers_ibfk_1` FOREIGN KEY (`advertiser_id`) 
      REFERENCES `jobs` (`advertiser_id`);

...is actually the opposite to what it should be. As it is, it means that you'd have to have a record in the jobs table before the advertisers. So you need to use:

ALTER TABLE `jobs`
  ADD CONSTRAINT `advertisers_ibfk_1` FOREIGN KEY (`advertiser_id`) 
      REFERENCES `advertisers` (`advertiser_id`);

Once you correct the foreign key relationship, your delete statement will work.

Cannot delete or update a parent row: a foreign key constraint fails - MYSQL

You get this error because the user you would like to delete has associated records within the appointments table. You have 2 options:

1. Delete the associated records from the appointments table first with a separate delete statement.

2. Add on delete cascade option to appointments_user_id_foreign foreign key. This option will automatically remove any associated records from the appointments table for the user to be deleted when you delete the user's record.

The modified fk statement looks like as follows:

... ADD CONSTRAINT `appointments_user_id_foreign` FOREIGN KEY (`user_id`) REFERENCES `users` (`id`) ON DELETE CASCADE;

The solution proposed by @Nebster technically removes the error message, but also enables having orphan records within the appointments table - appointments related to deleted users. Therefore, removing the foreign key is not a sensible option in my opinion.

I cannot delete a record Cannot delete or update a parent row: a foreign key constraint fails. How do I fix this?

The reason is cascade = CascadeType.ALL here

@ManyToOne(cascade = CascadeType.ALL)
@JoinColumn(name = "userId")
private User user;

It means that the User has to be deleted after deleting any of Ratings.

Better to use RatingEntity for the entity and RATINGS for the table name.

General rule

Never use any cascade with @ManyToOne part of the association!

Also always use fetch = FetchType.LAZY with @ManyToOne.

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "userId")
    private User user;

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "answer_id")
    private Answer answer;

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "question_id")
    private Question question;

How to solve Cannot delete or update a parent row: a foreign key constraint fails?

Something is referencing the User table with a foreign key. The full stack trace will likely tell you which table it is, or which constraint it is, from which you should be able to find out the table.

Once you identified the foreign key causing the problems you have the following options:

• remove the rows referencing the user you want to delete.
• update the rows referencing the user you want to delete to not reference that user anymore.
• change you schema to not have that foreign key. This is in most cases not a good idea, since it will leave you with dangling pointers in your database. But there are use cases for this approach.
• change the cascading behaviour of the foreign key.

MYSQL error code 1451: cannot delete or update parent row: a foreign key contraint fails

From the error, there is a foreign key constraint issue, that means that there is one or more rows in table golfbag that contains the primary key of the row to be deleted from table caddy as its foreign key.

Although there is a way to force delete but this is not advised as this will cause orphan records in table golfbag.

You can temporarily disable foreign key check before the delete query and enable it back after the delete is executed.

To disable foreign key check, use

SET FOREIGN_KEY_CHECKS = 0;

and to enable it, use

SET FOREIGN_KEY_CHECKS = 1;

Laravel 8 Cannot delete or update a parent row: a foreign key constraint fails

first, delete from bid table

bids::where('bids.loan_id', $id)->delete();

After that

Loan_requests::find($id)->delete();
session()->flash('status','Loan Request deleted successfully');
return redirect()->back();

ManyToMany - Cannot delete or update a parent row: a foreign key constraint fails (JAVA SPRING)

You can try writing Subject entity like this

@Entity
public class Subject{

    @ManyToMany(cascade =CascadeType.ALL)
    @JoinTable(name = "subjects_topic", joinColumns = @JoinColumn(name = "subject_id"), inverseJoinColumns = @JoinColumn(name = "topic_id"))
    private Set<Topic> topic = new HashSet<>();
}

And writing Topicentity like

     @Entity
        public class Topic{
        
           @ManyToMany(mappedBy = "topic", cascade = CascadeType.All)    
           private Set<Subject> subject= new HashSet<>();
     }

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