LINQ generating SQL not supported by SQL Server 2008R2 - linq

Question

I am using EF 6.1.3 in an ASP.NET MVC 5 project. Although my development environment is SQL Server 2012, QA and Production are on SQL Server 2008 R2.
I have a report that is to show the top 5 procedure codes utilized by a physician, so I have a simple entity with id, name, code1, code2,... code5.
There is a fair amount of logic in building the LINQ query, essentially I get a list of physician and a list of codes and join them. Here is the code that joins them and picks the top 5 codes:
var report =
from pr in providerRiskLevels
join nc in newCodes on pr.Provider.ProviderId equals nc.ProviderId
where pr.RiskCategoryId == RIskScoreIds.VisibleRisk
&& (filterRiskLevelNums.Contains(pr.RiskLevelNum))
&& (filterSpecialtyId == 0 || pr.Provider.Specialty.SpecialtyId == filterSpecialtyId)
select new ReportNewCodesEntity
{
ProviderId = pr.Provider.ProviderId,
ProviderName = pr.Provider.Name,
ProviderCode = pr.Provider.ProviderCode,
SpecialtyName = pr.Provider.Specialty.Name,
SpecialtyCode = pr.Provider.Specialty.SpecialtyCode,
RiskScore = pr.RiskScore,
RiskLevelName = pr.RiskLevelName,
RiskLevelNum = pr.RiskLevelNum,
NewCode1 = nc.Codes.OrderByDescending(c => c.Volume).FirstOrDefault().ProcedureCode,
NewCode2 = nc.Codes.OrderByDescending(c => c.Volume).Skip(1).FirstOrDefault().ProcedureCode,
NewCode3 = nc.Codes.OrderByDescending(c => c.Volume).Skip(2).FirstOrDefault().ProcedureCode,
NewCode4 = nc.Codes.OrderByDescending(c => c.Volume).Skip(3).FirstOrDefault().ProcedureCode,
NewCode5 = nc.Codes.OrderByDescending(c => c.Volume).Skip(4).FirstOrDefault().ProcedureCode
};
return report;
The problem is that the four Skip().FirstOrDefault() generate SQL with syntax not available on SQL Server 2008 R2:
OFFSET x ROWS FETCH NEXT 1 ROWS ONLY
where x = 1 to 4
I'm sure I can move this to a stored procedure (much better at T-SQL than LINQ), but since I have been trying to get a grip on LINQ, I was wondering if there was either:
A directive to tell LINQ the version of the target database so it would generate compliant code
Another method to extract these top 5 codes.
I do already have the codes ordered correctly in newCodes (see below) but was unable to pick them without the SKIP (which required it's own sort clause).
var newCodes =
from cc in codeCounts
group cc by
new {cc.ProviderId}
into g
select new ProviderNewCodesEntity
{
ProviderId = g.Key.ProviderId,
Codes = g.OrderByDescending (x => x.Volume).Take(5).ToList()
};
Best,
Scott

Answer 1

In order to get LINQ to generate compatible code, we simply edited the generated EDMX file (don't shriek yet , keep reading).
We found (on line 7)
<Schema Namespace="ComplianceRiskModel.Store" ProviderManifestToken="2012" Provider="System.Data.SqlClient" ...>
and changed it to
<Schema Namespace="ComplianceRiskModel.Store" ProviderManifestToken="2008" Provider="System.Data.SqlClient" ...>
To prevent losing this setting every time we refresh the model from the database, we are adding a build task to automatically update the EDMX file in a BeforeBuild target, as described at http://www.programmingmotility.com/2011/05/setting-providermanifesttoken-for-sql.html
Best,
Scott