How to return multiple SELECT sets from a stored procedure using FromSqlRaw Entity Framework Core 3.1

Question

I am currently having an issue with my returning values from the DB, I am using a SQL Server stored procedure and ASP.NET Core 3.1 to retrieve several SELECT sets.

Here's my stored procedure:

ALTER PROCEDURE [dbo].[MyProc]
    @BusinessModelID int
AS
BEGIN
    SELECT Id, Title 
    FROM [dbo].[Channels] 
    WHERE BusinessModelId = @BusinessModelID;

    SELECT Id, Title 
    FROM [dbo].[Problems] 
    WHERE BusinessModelId = @BusinessModelID;

    SELECT Id, Title 
    FROM [dbo].[CostStructures] 
    WHERE BusinessModelId = @BusinessModelID;

    SELECT Id, Title 
    FROM [dbo].[CustomerSegments] 
    WHERE BusinessModelId = @BusinessModelID;

    SELECT Id, Title 
    FROM [dbo].[KeyMetrics] 
    WHERE BusinessModelId = @BusinessModelID;

    SELECT Id, Title 
    FROM [dbo].[RevenueStreams] 
    WHERE BusinessModelId = @BusinessModelID;

    SELECT Id, Title 
    FROM [dbo].[Solutions] 
    WHERE BusinessModelId = @BusinessModelID;

    SELECT Id, Title 
    FROM [dbo].[Unfairs] 
    WHERE BusinessModelId = @BusinessModelID;

    SELECT Id, Title 
    FROM [dbo].[Values] 
    WHERE BusinessModelId = @BusinessModelID;
END

And here's my C# code:

var modelList = _dataContext.Set<BusinessToGet>()
                        .FromSqlRaw($"EXECUTE MyProc @BusinessModelID={businessModelId}")
                        .ToList();

The problem is that it should return several multiple sets but it is only returning one the Channels. What am I doing wrong?

Thanks in advance.

Answer 1

Update

In this case, there was duplicate primary keys across tables. Even though SQL below worked well in SQL-server, EF Core returned a lot of duplicate instances due to the fact that when EF Core sees an instance with Id = 1, it uses that for all sub-sequent instances with Id = 1.

A work-around is to use a keyless DTO for FromSqlRaw queries.

[Keyless]
public class BlogPostsCount
{
Id, 
    public int Id { get; set; }
    public string Title { get; set; }
}

https://docs.microsoft.com/en-us/ef/core/modeling/keyless-entity-types?tabs=data-annotations

---

Using UNION should solve this issue. If datatypes varies between tables, you may need to cast column values as well in order to make a uniform result. If you have duplicates across tables, and needs all, use UNION ALL .

SELECT Id, Title FROM [dbo].[Channels] WHERE BusinessModelId = @BusinessModelID
UNION
SELECT Id,Title FROM [dbo].[Problems] WHERE BusinessModelId = @BusinessModelID
UNION
SELECT Id, Title FROM [dbo].[CostStructures] WHERE BusinessModelId = @BusinessModelID
UNION
SELECT Id, Title FROM [dbo].[CustomerSegments] WHERE BusinessModelId = @BusinessModelID
UNION
SELECT Id, Title FROM [dbo].[KeyMetrics] WHERE BusinessModelId = @BusinessModelID
UNION
SELECT Id, Title FROM [dbo].[RevenueStreams] WHERE BusinessModelId = @BusinessModelID
UNION
SELECT Id, Title FROM [dbo].[Solutions] WHERE BusinessModelId = @BusinessModelID
UNION
SELECT Id, Title FROM [dbo].[Unfairs] WHERE BusinessModelId = @BusinessModelID
UNION
SELECT Id, Title FROM [dbo].[Values] WHERE BusinessModelId = @BusinessModelID