How can I implement a foreign key in SQLite? I was thinking something like this: CREATE TABLE job (_id INTEGER PRIMARY KEY AUTOINCREMENT, employer_id INTEGER, ...); CREATE TABLE employer(_id INTEGER, employer_name TEXT NOT NULL, ...); Where employer_id is the _id from the table employer. Would this work? Is there another fast, maybe ...
I recently changed my code to make reference to the getHibernateTemplate(), and now my forms don't seem to save correctly, here's the code: public void saveForm(EcoFormFill form, int userId) throws RemoteException { User tmpUser = (User)getHibernateTemplate().load(User.class, new Integer(userId)); form.setUser(tmpUser); ...
I got two Entity: Customer Entity @Entity public class Customer { @Id @GeneratedValue(strategy = GenerationType.AUTO) private Long id; private String name; @OneToMany(mappedBy="customer", cascade=CascadeType.ALL) private List<Facility> facilities; //Setter and Getter for name and facilities public void addFacility(Facility facil...
I've seen posts on SO and through google stating that with Mysql you cannot have multiple foreign keys of the same name. My issue is how do I reference the same column from one table in multiple other tables. In my case I have a FAMILY table that contains FAM_ID. I want this to be a foreign key in my DOCUMENTS and CONTACT tables because ...
Hi, I've been searching for an answer, but no luck so far... I want to perform bulk operations on a database with potentially millions of records, reading the PostgreSQL guide: '13.4 Populating a Database' 1, it suggests removing indexes and foreign-key constraints to speed up the copy operation. I'm trying to accomplish this using JDB...
When table was set up with a column that has a foreign key and is set to cascade (delete child when parent is deleted) what would the sql command to change this to be restrict? (can't delete parent if it has children) ...
I get error 1452 when trying to do this: ALTER TABLE test.potovanja ADD CONSTRAINT usr_ind FOREIGN KEY (username) REFERENCES test.users (username) (Error Code: 1452 Cannot add or update a child row: a foreign key constraint fails (test., CONSTRAINT #sql-1110_2_ibfk_1 FOREIGN KEY (username) REFERENCES users (username))). Reference key...
I have a situation and would appreciate some help. I have two tables - Error and Warning: Error : Err_no, pattern(pk=Error_no) Warning : War_no, pattern(pk=War_no) Based on these tables I have to decide on the resolution and I have a separate table doing this: Resolution : Code_no, resolution I want to keep Code_no as foreign key...
I have a table called [Sectors], which stores industry sectors. [SectorId] is defined as an INT and is the primary key of this table. These sectors are referenced throughout the database using the primary key, but there are no foreign key constraints for this primary key in the other tables. Now there are 2 sectors in this table that no...
hi, my model is basically a chain of objects linked by a foreign key: class Object1(object): object1_id = models.AutoField() object1_name = models.CharField() class Object2(object): object2_id = models.AutoField() object2_name = models.CharField() object1 = models.ForeignKey(Object1) class Object3(object): obje...
Hello! I have such model: class Place(models.Model): name = models.CharField(max_length=80, db_index=True) city = models.ForeignKey(City) address = models.CharField(max_length=255, db_index=True) # and so on Since I'm importing them from many sources, and users of my website are able to add new Places, I need a way to...
I have two classes Message and User. Message has sender_id and recipient_id both foreign keys for User. How to build relationship where I'll be able to get user for both sender and recipient, like @message.sender.name and @message.recipient.name I tried to do it by this way: class Message < ActiveRecord::Base belongs_to :sender, :...
I have a model defined as class A < ActiveRecord::Base belongs_to :b belongs_to :c end How do I create a new instance of A associated with both b and c. I've got the ids for b and c. ...
Title says it all :) Thanks ;) ...
How can I delete duplicate rows from a MySQL table when a foreign key relationship has already been setup up on those rows. Can the duplicates be merged somehow and then foreign key updated with the new value? ...
I have foreign keys set in a mysql db. I have backed up my db from one server to a new one. Both the new and the old server use phpmyadmin. On the old server, y used to have a link in the view of a table from the foreign key to the respective register in the other table. An html link that leads me to the register in the other table. But ...
It seems that when a child object has a reference to its parent in its setter, it fails to get initialized unless the foreign key is given first in the parameter hash. class Bot < ActiveRecord::Base has_many :items end class Item < ActiveRecord::Base belongs_to :bot def name=(text) write_attribute(:name, "#{self.bot.name}'s ...
I wish to have a foreign key in a table but I have no idea how to do it. I wish have a UserID Column in the "wall" table so that I can link back and get the userid's details etc. How would i go about doing this? Wall Table: Users Table: ...
I was wondering, What will be my motivation to use constraint as foreign key in MySQL, as I am sure that I can rule the types that are added? Does it improve performance? ...
I'm building a small application and setting up foreign key relationships between tables. However I'm confused as to WHY I really need this? What is the advantage - does it assist me when writing my queries that I don't have to perform any joins? Here's an example snippet of my database: +-------------------+ | USERS | +----...