foreign-key-relationship

I have a created a WPF application with Entity framework 4.0. When i am trying to insert record in PhoneNumber Table it inserts first record successfully. But, when i loop through some List and try to insert another item into PhoneNumber table it Insert the record but shows error as: InvalidOperationException was handled by user code: The changes to the database were committed successfully, but an error occurred while updating the object context. The ObjectContext might be in an inconsistent state. Inner exception message: A referential integrity constraint violation occurred: The property

I have come to a conclusion that I should define both Independent Association and Foreign Key Association in My Code-First design. e.g: public class Book { public int ID {get; set;} public int AuthorID {get; set;} [ForeignKey("AuthorID")] public Author Author {get; set;} } With the above definition, do I have to update AuthorID when I want to change the book's author, Or just using the below line is enough? myBook.Author = author; Am I going to get a null exception on the above line if that is the first time I'm defining an author for the book? (Does EF initialize book's author automatically

So I've inherited some django. The mySQL table is simple enough where parent is NOT a FK relationship just the "Parent" id: CREATE TABLE `Child` ( `id` int(10) unsigned NOT NULL AUTO_INCREMENT, `parent` int(10) unsigned NOT NULL, `name` varchar(255) NOT NULL, UNIQUE KEY `id` (`id`) ) ENGINE=InnoDB AUTO_INCREMENT=24; But then the originator did this.. class Child(models.Model): """Project Child information""" id = models.AutoField(primary_key=True) parent = models.ForeignKey(Parent) name = models.CharField(max_length=255) class Meta: managed = False Admittedly I am NOT a SQL Jockey but I know

I am trying to create a database for work. I have two different types of users: internal and external. Each type has different properties so I just created two separate tables for them. In my internal table I have the following fields: f_name VARCHAR(32), l_name VARCHAR(32), empl_status_id INT, admin_grp_id INT, reliab_status_id INT, supv_id INT And my external table has the following: f_name VARCHAR(32), l_name VARCHAR(32), email VARCHAR(32), phone VARCHAR(20), org_id INT, supv_id INT I realize that I could probably create a separate table that contains the names of the users and a foreign

Topic MariaDB InnoDB Foreign Key Issue Want to start off by saying I'm new to InnoDB and spent all day reading posts yesterday I've tried multiple things along the way to get me where I am now so am I hosed or is there a way out of this dark forest. I have a table that is central to a number of tables in my data model. So something along these lines: create table users (id int not null auto_increment , username varchar(255) NOT NULL , password varchar(255) NOT NULL , active int NOT NULL , PRIMARY KEY (id)) ENGINE=InnoDB COLLATE=utf8_unicode_ci; Decided to clean up some DELETE / UPDATE clauses