entity-relationship

Export/Import Specific Data From Entity Model

Hey Guys, Just wanted to get some ideas on what would be the best way to go about backing up and restoring part of my entity model. We basically have an entity model of our database, and would like to give the user the opportunity to backup sections of the database. Some things that have to be considered are as follows: All tables hav...

Why are my manually created Linq2Sql table relationships showing up in code?

I have some views that I'd like to relate together in my Linq2Sql DBML file. I've right clicked, selected "Add association" and manually created the associations from children to parents, for example: Customer.TypeId -> CustomerTypes.Id But I cannot do this in my code: from c in Customers select c.Type.Name Any clues? If the relat...

Write/get data from joining table in many-many relation

Hi, is there a way to get or write data to/from joining table in many to many relation? I have two tables joined by third. Question one: How can i GET data from the joining(middle) table, when i'm retrieving data in similar query //table1 is "root" table - containing records related to table3 //table2 is joining/cross table //table3 c...

Hibernate @OneToMany without a separate join table

Consider the following database schema: create table UserGroup ( id int not null auto_increment, name varchar(200), primary key(id)); create table User ( id int not null auto_increment, name varchar(200), groupId int not null, primary key(id)); User.groupId = UserGroup.id, so a user can only be a member of one group, but a usergroup ...

Using relationship/foreign key with linq2sql?

Hi there, Can anyone help? I have a created a relationship between my Reservation(prim key) and Insurance(for key) tables and imported into linq2sql and checked my automatically created c# files and sure enough i have reservation.MyFieldNames etc etc PLUS reservation.Insurance which is my relationship but reservation.Insurance i can't ...

ERD tool that generates MySQL schema

Hi, I'm looking for a tool that will allow me to draw an ERD and will generate the SQL that creates the corresponding MySQL schema. Additional requirements are: Runs on windows Zero cost Bonus points if it runs on Ubuntu too, but this isn't a 'must-have'. Thanks, Don ...

How to visualize the relationship of tables in an Oracle database

I know in Access there is a way I can visualize the relationship between tables in a diagram - kind of like an ER diagram. I am new to Oracle. I am wondering if I can do the same/similar thing with Oracle. Could someone give some suggestions? ...

Efficient way to populate Entify Framework query with related objects?

I'm using EF for a set of objects and want to query one type of object with the matching entries from two other tables. This is to dump the query into an XML output. At first, used a join since in the original data each Employee always had 1+ instances of a Computer object (solution #2 below), but it's not necessarily true. For purpos...

ADO.NET Entity Data Model: Auto-generated classes.

Hi, I have a table structure like the following: Companies Addresses ********* ********* ID ID AddressID ... BillingAddressID ... AddressID and BillingAddressID are foreign keys which are present in the Addresses table. When I generate my model based on this table instead of getting w...

Generating Clean Business Object Classes from a horrible data source

I'm starting with a blank slate for a layer of business/entity classes, but with an existing data source. Normally this would be cake, fire up Entity Framework, point it at the DB, and call it a day, but for the time being, I need to get the actual data from a third party vendor data source that... Can only be accessed from a generic O...

Getting Error 3007 when I add my Entity Model

I am getting an error 3007 when I add my entity model to my solution. I found these links: Good explination Short answer About this error: Error 1 Error 3007: Problem in Mapping Fragments starting at lines 89, 94: Non-Primary-Key column(s) [Person_ID] are being mapped in both fragments to different conceptual side propert...

Why is this Core Data example crashing?

I have a model where I have a Person entity and a Picture entity. In my Picture entity I have a property that is a relationship to a Person. I would like to have an example about how to add a Picture to a Person because what I did doesn't work. -(BOOL)savePicture:(NSString *)urlPicture:(Person *)person{ SettingsSingleton *userSettings ...

CakePHP joining Models between two tables, twice

I have a question about how to set up the relations between two models when they join to each other in two different regards. I'll give an example of the problem I've got: Users (id, name) Messages (id, message, from_user_id, to_user_id) (In my case, it's not users nor messages, but this hopefully illustrates the problem in a simpler...

Set a relationship with Core Data

I have two entities that are connected through a one-to-many relationship, let's say CategoryEntity and ItemEntity. The relationship is optional for CategoryEntity (there can be categories without items), but required for every ItemEntity. At the app's loading, the Categories already exist in the store, and I want to import ItemEntities ...

NSPredicateEditor and relationships

I've seen that every predicate that works in a query with a relationship contains at the start the words ANY or ALL (ie: ANY tags.name LIKE[c] "car"), the fact is, if I remove it (ie: tags.name LIKE[c] "car"), the result is wrong or I get a message like this one : Can't do regex matching on object. Since i'm using an NSPredicateEditor t...

Entity Framework: Assign entity to property of another entity

Hi, I have these entities (this is just an abstraction I created for this post): Language District Description These are the references between them: District * - 1 Language Description * - 1 Language District 1 - 1 Description If I fetch like this: var myFetch = from c in context.Districts where c.Id = 10 ...

Can I use a C# collection to hold class instances with self-referential relationships?

Hi, I need to model in memory a collection web files, but that relationships between them. That is file A (e.g. html) may have a link to file B (e.g. css) and file C (e.g. javascript). Also file D may also require file B. If I wanted to delete file A I would need to make sure any files it uses (e.g. file B) is not also being used ...

How to create an NSFetchRequest which filters Core Data objects based on attributes AND relationships?

Hello! I have a Core Data model setup like so: Blockbuster Entity To-Many relationship to DVD entities. DVD Entity title attribute (string) To-One relationship to a parent Blockbuster entity A single Blockbuster can have multiple DVD's inside of it (To-Many). Each DVD can only be part of a single Blockbuster (To-One). There ar...

Entity Relation notation in text

Is there a standard (non-graphical) notation for Entity Relationships? right now I'm using my own janky notation: User >> Photo , (1-many) User > Profile , (1-1 hasOne) Profile < User , (1-1 belongsTo) Photo << User , (many-1 belongsTo) Photo <> Tag , (many-many) ...

Override targEntity in descendant entity bean

I have two separate databases that contain a report and reportItems table. The table structure is the same for both databases. I have a session bean that needs to write to each database / table. In order to keep the code simple I want the session bean to work with a base entity bean that then goes to the appropriate table. To accomplis...