nTier structure and linked table

Imar · May 4th, 2009, 04:57 AM

There is no "right solution".... It all depends on your object model, your entities, your data structure and your prior knowledge of this technology.

Without knowing more about your database and object model, I can't recommend much....

Imar

il_dandi · May 4th, 2009, 05:11 AM

Suppose that I've the same structure of your example!

ContactPerson -> JOINED -> MailAddress

1 Person -> X Mail Address

If I have an entity named ContactPerson and I whant to know field's value of INNER JOIN records (of Address table) .... what I have to do??

Thanks

Imar · May 4th, 2009, 05:23 AM

There are many ways to do it, but one way is this:

SPROC (all pseudo)

@id int
SELECT * FROM Contact WHERE Id = @id
SELECT * FROM Address WHERE ContactId = @id

This gives you two result sets.

Then in your class Contact class:

// Get a reader based on the sproc
// Fill contact with data from the reader.
// Then fill the contact:
myContact.Address = new Address(myReader.NextResult());

The Address constructor accepts a IDataReader that it uses to fill in the data.

For more info on NextResult: http://msdn.microsoft.com/en-us/libr...extresult.aspx

Imar

il_dandi · May 4th, 2009, 05:13 PM

Excuse me Imar.... I've made many test

using the objects of your example

ContactPerson contact = new ContactPerson();

contact = ContactPersonManager.GetItem(4);

now I've "contact" .... how can I view the addresses linked ?

Thanks

Imar · May 5th, 2009, 03:47 AM

Have you read the 6-part article series that goes with the code download? The article is the main asset; the code just a working example of what's exaplained in the articles. You shouldn't just download and use the code without understanding what it's all about.

If you read the articles closely, you find somehting like:

myContact.Addresses

as the answer to your question.

Cheers,

Imar

il_dandi · May 5th, 2009, 03:51 AM

Thanks Imar! I've read articles many times ... and now I would like to make test on your example ... for allow me to work on nTier structure ... this is the firt time for me!

Could you help me ... starting with this code

ContactPerson contact = new ContactPerson();

contact = ContactPersonManager.GetItem(4);

now I've "contact" .... how can I view the addresses linked ?

Thanks for help me!!

Imar · May 5th, 2009, 03:54 AM

I just told you in my previous post:

contact.Addresses

contains eum, well, the addresses.....

Imar

il_dandi · May 5th, 2009, 04:02 AM

Thanks!!!

But I have to cast it? for allow me to do contact.address.something?

address addr = (address)contact.address;

Thanks

Imar · May 5th, 2009, 04:33 AM

Why would you? Take another look at the source and the articles. You'll see that Addresses is an AddressCollection......

Imar

il_dandi · May 5th, 2009, 05:36 PM

Uffffff

I've inserted 3 records with ID 2883 in addresses table

but in debug mode I see

- contact.Addresses Count = 0 Spaanjaars.ContactManager.BusinessEntities.Address Collection

but in addresses table I've

66 q q 111 11 11 1 2883 <Binary data>
67 2 2 11 11 11 1 2883 <Binary data>
68 2 2 11 11 11 1 2883 <Binary data>

with this code:

ContactPerson contact = new ContactPerson();

contact = ContactPersonManager.GetItem(2883);