foreign-keys

LINQ to SQL - Nullable<int> ForeignKey = An attempt was made to remove a relationship between...?!

Hi. I have a data model like this: [Table(Name = "DayWorks")] public class DayWork { [Column(DbType = "Int NOT NULL IDENTITY", IsPrimaryKey = true, IsDbGenerated = true)] public int ID { get; set; } ... /* no any EntitySet here for extensionable model purposes (really need) */ } [Table(Name = "Documents")] public class Document { ...

How should I manage my many-to-many relationships?

Hello all, I have a database containing a couple tables: files and users. This relationship is many-to-many, so I also have a table called users_files_ref which holds foreign keys to both of the above tables. Here's the schema of each table: files -> file_id, file_name users -> user_id, user_name users_file...

How to configure reference to be deleted on parent table update?

I have two tables: info: ID, fee_id and fee: ID, amount and a reference between them (SQL Server 2008): ALTER TABLE info WITH CHECK ADD CONSTRAINT FK_info_fee FOREIGN KEY(fee_id) REFERENCES fee (ID) ALTER TABLE info CHECK CONSTRAINT FK_info_fee GO How to configure this reference that way so a record in fee will be deleted if inf...

Sql server Stored Procedure

I m passing a variable to stored procedure, i want the proc to make a look up to another table and get the primary key of the table and insert that value to the table. Table A: pk_id int, user varchar Table B: userKey int locationKey int Someotherthings varchar Table C: pk_id int, Location varchar When i invoke sp_howto, and pa...

design of orm tool

Hello , I want to design a orm tool for my daily work, but I'm always worry about the mapping of foreign key. Here's part of my code: using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Data; namespace OrmTool { [AttributeUsage(AttributeTargets.Property)] public class ColumnAttrib...

Does Rails need database-level constraints?

I have the same problem as in the following post. So I am wondering, why doesn't Rails support generating foreign keys by default? Isn't it necessary? Or are we supposed to do it manually? ...

MySQL composite unique on FK's

I want to implement the following constraints in mysql: create table TypeMapping( ... constraint unique(server_id,type_id), constraint foreign key(server_id) references Server(id), constraint foreign key(type_id) references Type(id) ); This throws a 'ERROR 1062 (23000): Duplicate entry '3-4' for key 'server_id'' when...

how to force nhibernate to set the foreign key of the child item?

i have a collection in the mapping: <bag name="Values" cascade="all-delete-orphan" lazy="false" inverse="true"> <key column="[TemplateId]"/> <one-to-many class="MyNamespace.Value, MyLib"/> </bag> the Value object has a foreign key [TemplateId]. both entities has their generator set to "identity". when i call session.Save() for th...

Retain a list of objects and pass it to the create/edit view when validation fails in ASP.NET MVC 2

I am binding a Foreign key property in my model. I am passing a list of possible values for that property in my model. The model looks something like this: public class UserModel { public bool Email { get; set; } public bool Name { get; set; } public RoleModel Role { get; set; } public IList<RoleModel> Roles { get; set;...

How to identify foreign key in MySQL DB?

How to identify foreign key in MySQL DB Table? ...

[Django] How to find out whether a model's column is a foreign key?

I'm dynamically storing information in the database depending on the request: // table, id and column are provided by the request table_obj = getattr(models, table) record = table_obj.objects.get(pk=id) setattr(record, column, request.POST['value']) The problem is that request.POST['value'] sometimes contains a foreign record's prima...

error in mysql syntax

while executing the following query, i get an error that there's an error in the syntax near line 9. since i'm using mysql workbench, i can't really figure out what could be wrong: CREATE TABLE IF NOT EXISTS `proquotes`.`thquotes` ( `idQuotes` INT NOT NULL AUTO_INCREMENT , `vAuthorID` VARCHAR(8) CHARACTER SET 'utf8' NOT NULL , ...

MySQL foreign key creation with alter table command

I created some tables using MySQL Workbench, and then did forward ‘forward engineer’ to create scripts to create these tables. BUT, the scripts lead me to a number of problems. One of which involves the foreign keys. So I tried creating separate foreign key additions using alter table and I am still getting problems. The code is below (t...

django models : How to have variable number of foreign keys in a model ?

For instance, Model Resume contains variable number of Model Project 's, What should be my models and relationships between them to achieve this ? Thanks in advance. ...

Sqlite / SQLAlchemy: how to enforce Foreign Keys?

The new version of SQLite has the ability to enforce Foreign Key constraints, but for the sake of backwards-compatibility, you have to turn it on for each database connection separately! sqlite> PRAGMA foreign_keys = ON; I am using SQLAlchemy -- how can I make sure this always gets turned on? What I have tried is this: engine = sqlal...

Entity Framework - Insert with foreign key

Hi, Apologies if there is clear answer for this somewhere. But I can't insert into a simple table due to it containing a foreign key. Task Table TaskId (PK) Description StatusId (FK) Into which I try to insert like so: Task t = new Task(); t.Id = 1234; t.Title = "foo"; t.Status = db.Status.ToList().F...

Many-to-Many Relationships in MySQL

I've been reading up on foreign keys and joins recently, and have been pleasantly surprised that many of the basic concepts are things I'm already putting into practice. For example, with one project I'm currently working on, I'm organizing word lists, and have a table for the sets, like so: `words` Table `word_id` `headword` ...

Problems getting foreign keys working in MySQL

I've been trying to get a delete to cascade and it just doesn't seem to work. I'm sure I am missing something obvious, can anyone help me find it? I would expect a delete on the 'articles' table to trigger a delete on the corresponding rows in the 'article_section_lt' table. CREATE TABLE articles ( id INTEGER UNSIGNED PRIMARY KEY...

how to create table which has a column from another table in mySQL

i want to create a table : products which looks like (these are columns name) Id Name Category-id Description now Category-id column gets the values from another table category which looks like Id Name Description now category.Id is used in products.Category-id how to do this in mySQL ...

JPA : many-to-many - only one foreign key in the association table

I mapped two classes in a ManyToMany association with these annotations : @Entity @Inheritance(strategy=InheritanceType.TABLE_PER_CLASS) public abstract class TechnicalItem extends GenericBusinessObject implements Resumable{ @SequenceGenerator(name="TECHNICAL_ITEM_ID_GEN", sequenceName="TECHNICAL_ITEM_ID_SEQ") @Id @Column(n...