Joining two tables with specific columns in nhibernate - nhibernate

Question

I have two table: Customers and Products
public class Customers
{
public virtual int Id { get; set; }
public virtual string CName { get; set; }
public virtual int Age { get; set; }
public virtual string Address { get; set; }
public virtual int Salary { get; set; }
}
public class Product
{
public virtual int Id { get; set; }
public virtual string PName { get; set; }
public virtual Customers CustomerID { get; set; }
public virtual int Amount { get; set; }
}
whit this Values in DB:
------------Customer Table----------------
| id | CName | Age | Address | Salary |
------------------------------------------
| 1 | Ben | 18 | a | 1000 |
| 2 | Mark | 20 | b | 2000 |
| 3 | Ben | 18 | a | 3000 |
| 4 | Ben | 19 | c | 4000 |
| 5 | Mark | 20 | b | 5000 |
| 6 | Jane | 21 | d | 6000 |
------------Customer Table----------------
| id | PName | CustomerID_id | Amount |
------------------------------------------
| 1 | A | 1 | 5 |
| 2 | B | 2 | 10 |
| 3 | C | 1 | 15 |
| 4 | D | 2 | 20 |
| 5 | E | 2 | 25 |
| 6 | F | 6 | 30 |
| 7 | G | 6 | 40 |
When I run this query in SQL Server Management:
SELECT CName , Amount
FROM [TestNhibernate].[dbo].[Product]
Inner Join [TestNhibernate].[dbo].[Customers]
on [TestNhibernate].[dbo].[Product].[Customerid_id]
= [TestNhibernate].[dbo].[Customers].[id]
SQL result is:
-------------------
| CName | Amount |
-------------------
| Ben | 5 |
| Mark | 10 |
| Ben | 15 |
| Mark | 20 |
| Mark | 25 |
| Jane | 30 |
| Jane | 40 |
And when I run this query
SELECT CName , Sum(salary) as SumSalary, sum(amount) as SumAmount
FROM [TestNhibernate].[dbo].[Product]
Inner Join [TestNhibernate].[dbo].[Customers]
on [TestNhibernate].[dbo].[Product].[Customerid_id]
= [TestNhibernate].[dbo].[Customers].[id]
Group By Cname
results is :
----------------------------------
| CName | SumSalary | SumAmount |
----------------------------------
| Ben | 2000 | 20 |
| Jane | 12000 | 70 |
| Mark | 6000 | 55 |
----------------------------------
How can I express that in NHiberante query?
UPDATE: some attempts
I try this code
session
.QueryOver<Product>()
.JoinQueryOver<Customers>(p => p.CustomerID)
.SelectList(w => w
.Select(x => x.Amount)
.Select(z => z.CustomerID))
.List<object[]>()
this is done but when i write this code
session
.QueryOver<Product>()
.JoinQueryOver<Customers>(p => p.CustomerID)
.SelectList(w => w
.Select(x=>x.Amount)
.Select(z=>z.CustomerID.CName))
.List<object[]>()
doesn't work!

Answer 1

Based on the information in the question, there is some draft of the QueryOver syntax, which should help to understand. Firstly we should create some DTO, representing the result:
public class ProductDTO
{
public virtual string ClientName { get; set; }
public virtual decimal SumSalary { get; set; }
public virtual decimal SumAmount { get; set; }
}
Now, we should have business model with a bit more standard naming:
public class Product
{
...
// instead of this
//public virtual Customers CustomerID { get; set; }
// we should use
public virtual Customers Customers { get; set; }
}
Personally I would rather see Customer than Customers... but still better than CustomersID
Because our mapping here must be <many-to-one representing reference relation, not just <property - representing the value type / integer.
Now the query:
// to have access to client name
Customers client = null;
// that would be result - used for proper columns aliasing
ProductDTO dto = null;
var result = session.QueryOver<Occupation>()
.JoinQueryOver<Customers>(p => p.Customers , () => client)
.SelectList(w => w
// SUM
.SelectSum(x => x.Amount)
.WithAlias(() => dto.SumAmount)
.SelectSum(x => x.Salary)
.WithAlias(() => dto.SumSalary)
// GROUP BY
.Select(x => client.CName)
.WithAlias(() => dto.ClientName)
)
// we do have enough info to ask NHibernate for
// fully typed result - Product DTO
.TransformUsing(Transformers.AliasToBean<ProductDTO>())
.List<ProductDTO>();
That should give some idea how to do querying with NHibernate. Also, I would suggest to extend Customer with IList<Products>