My understanding is that there is a ParentId in CutomerAddress which will be either the AccountId or ContactId. Also, the Account entity has an AddressId.
How does the relationship flow between Account and CustomerAddress? Is the Account referencing CustomerAddress?
If I create a new Account/Contact that has the same CustomerAddress of a previously existing Account, will the same AddressId be used or a different record will be created in CustomerAddress for this Account/Contact? Usually, at least the Telephone number column will be different which will result in creating a new record but if all fields are similar will a new CustomerAddress record still be created?
No, CustomerAddress records cannot be shared. The relationship between Account : CustomerAddress and Contact : CustomerAddress is 1:N. There is no N:M intersection.
It makes it simple to understand, but the downside is we may end up with quite some duplicated data.
Related
There is an Attribute called ParentId in CustomerAddress Entity. Will this contain the AccountId or ContactId?
If yes, if I create another Account or Contact with the exact same Address Details, a new record will be created anyway as the ParentId will be different?
Or if the AddressId is going to be stored in the Account Entity, can the same address be used by different accounts or even contacts?
Can Account1 and Account2 or Account1 and Contact2 have the same address?
The relationship between Address entity and Account or Contact entities is one-to-many. It means that one Account can have multiple Addresses, but one Address can be assigned to only one Account.
Answering to your question: no, multiple Account and Contact records can not share the same Address record.
I have created a table that contains Ticket information, with an id, message body, user id and department id.
I would like to be able to limit access to these tickets, such that only users from the corresponding department can access the relevant tickets, and can not view other department's tickets.
I have attempted to make an updatable view for each department and granting select on this, but it does not work very well.
Is there a simple way to achieve this kind of role based access?
In the Spring/Hibernate/Java/Tomcat app I'm writing I have a OneToMany relationship between an Organization and its Contacts.
Organization 1:M Contact (has foreign key org_id)
In Organization I have this field:
#OneToMany(mappedBy="organization")
private List<Contact> contacts;
In Contact I have this field:
#ManyToOne
#JoinColumn(name="org_id")
private Organization organization;
All is working OK so far. Now I'm adding the concept of an Offer. The Offer can be made by an Organization, and you speak with the designated Contact for that particular Offer.
Offer has foreign keys for its organization (org_id) and designated contact (contact_id).
So far, the Offer would look like:
#OneToOne
#JoinColumn(...)
private Organization offering_org;
#OneToOne
#JoinColumn(...)
private Contact offering_contact;
Here comes the point of my question. I've already annotated the Contact class for use with Organization. If I try to persist the Offer object in the usual Hibernate way, I'll need to store copies of an Organization object and a Contact object into the Offer object. This seems to conflict with my existing Organization : Contact use of the two Java classes. For example, if I've a 1:1 with Offer, if I put this into the Contact class do I get an optional use of either or a mandatory simultaneous use of both?
Since the Offer is yet another relationship, do I need to write a data transfer object version of Contact for use in the Offer relationship?
Thanks,
Jerome.
Perhaps I do not fully understand the problem but I'd just do something like this:
// contact & organization being already persisted entity objects
Offer offer = new Offer();
offer.setOffering_org(organization);
offer.setOffering_contact(contact);
// Persisting the new Offer object to the database,
// implicitly making the relations.
service.saveObject(offer);
I see no reason to create copy(s) of the organization object?
It just happens to be that the collection of "contacts" in the Organization object can also be a Contact within one or more Offer objects.
I'm thinking that my original question is kind of stupid. What I did try is to put this in Offer.java:
#Column(name="org_id")
private Long orgId = null;
#Column(name="contact_id")
private Long contactId = null;
I fill orgId manually because an offer is always tied to the user's Organization. It is a hidden field in the web page.
I put a SELECT filled with appropriate Contact objects (contact.id, contact.name) in the web page.
When the web page is submitted the Offer's orgId and contactId fields are filled in the #ModelAttribute parameter. This takes me where I want to go.
To address the comments of Mr. mspringer, your example could work (you illustrated a "create new" situation) if I were willing to use an Organization or Contact list in my Offer object. It is also somewhat the topic of my original question. But since I see that I don't really want to play with the expanded objects within Offer, nor do I wish to, I can avoid the topic of my original question.
Thanks to all who looked at my exercise in confusion.
What's the best way to handle this scenario?
I have a customer Model(Table) contains contact info for customers
I have Prospect Model(Table) contains contact info for store visitors that aren't customers
I have an Opportunity Model (Table) when either a customer or Prospect visits the store.
In my view I want to generate a new oppportunity. An opportunity can only contain either 1 customer association or 1 prospect association but not both.
In my opportunity model I currently have both the customer and prospect as nullable foreign Id's and and navigation properties. I also have an ICollection<> for Customers and Prospects on the opportunity model.
Is this the right way to do handle a conditional association?
When it comes to the view, I'm stuck on how would I make the customer or prospect association?
I am a computer science student, and this is my understanding on DB relationships:
Since you have two types of "People" - Customer - and Prospect - you could potentially have a table called "Person". In the Person table any common data among both entities would be stored (FirstName, LastName, Address1, Address2, City, State, Zip, etc...).
To indicate that a Person is a Prospect, you would have a Prospect table, which would have a PersonId to link to the person table. You can store more specific attributes about a prospect in this table.
The same would go for a Customer - you would have a Customer table - that would have a PersonId column to link to the Person table, and any specific attributes for the Customer entity.
Now you have a database in which you can derive other entities ... say an Employee entity > you have your base Person Entity to start from. And your Employee table would link back to it, and also have other custom columns for employee specific data.
Does that make sense?
Or maybe I'm going about this all wrong :). Please correct me if I am wrong as I am still a student.
I think you are stuck because you now have two fields on an "Opportunity" record (Customer OR Prospect), one of which MUST be null. With the model I proposed, your Opportunity would link to a Person, in which you can define custom business rules restricting say... an Employee Opportunity (which actually might not be a bad idea).
For the referenced Person in your Opportunity model, it would not be an ICollection (since you specifically said that an opportunity can have ONLY one person). It would simply be a single class such as:
private virtual Person Person { get; set; }
EDIT: If you don't want to restructure your entire database, you could just have a dropdown that asks what type of Opportunity this is (Customer, or Prospect). Based on the selection, you would add a foreign key in your Opportunity table to link to your [Customer or Prospect].
I have two tables, in which one user can have several contacts:
User(UserId, UserName)
Contact(UserId, ContactId)
Suppose I would like to get all the ContactNames from the UserNames in the User Table by the Userid.
Note that the Contact table cannot be seen in the current data context, it has been turned into a many to many relationship
How can I do the query？
What If I need to insert or delete?
I tried the "include" method but it does not work. Do you have any suggestions?
Thank you very much.
var id = 1; // id to find
context.Users
.Where(x=>x.UserId = id)
.SelectMany(x=>x.Users)
.Select(x=>x.UserName)
.ToArray();
After generation from db your model has 2 sub-collections: Users and Users1.
One of it corresponds to users, that are contacts for current user.
Another stores users, that current user is contact for.
You can rename them to represent their meaning to Contacts and ContactsFor via editor.
If you still want to have 2 types instead of Type+(Many-To-Many Ref), then in editor you can delete reference, create new entity Contact, setup all mapping, add references. After all this is done - you will have model look like this:
To Achieve this:
Delete Many-To-Many reference
Crete new Entity Contact
Add properties ContactId and UserId, set StoreGeneratedPattern to none
Add mappings for Contact
Add associations for Contacts and ContactFor
But it's not that easy.