Need to convert sql statement into Entity Framework equivalent - sql-server

Question

Given the following tables:
InstrumentLogs
InstrumentLogId (PK, int, not null)
InstrumentId (FK, int, not null)
LogDate (datetime, not null)
Action (string, not null)
Instruments
InstrumentId (PK, int, not null)
CountyId (FK, int, not null)
Counties
CountyId (PK, int, not null)
StateFips (FK, int, not null)
Name (string, not null)
States
StateFips (PK, int, not null)
Name (string, not null)
I need to figure out how to write this SQL query using Entity Framework:
select s.StateName, count(*) as total
from instruments as i
join counties as c on i.CountyID = c.CountyID
join states as s on s.StateFIPS = c.StateFIPS
where i.InstrumentID in
(select i1.InstrumentId from InstrumentLogs as i1 where i1.action = 'review' and
i1.logdate in (select max(logdate) from instrumentlogs as i2 where i1.instrumentid
=i2.InstrumentID group by i2.instrumentid))
group by s.StateName
I tried something along the lines of:
_context.Instruments.Include(i => i.County.State)
.Where(i => _context.Logs.Where(l => l.Action == 'review'
&& _context.Logs.Where(l2 => l2.InstrumentId == l.InstrumentId).Max(l2 => l2.LogDate) == l.LogDate).GroupBy(i => i.County.State.Name)
.Select(g => new { State = g.Key.Name, Total = g.Count() });
However, EF doesn't like this. I wind up with the error stating that only primitive types or enumeration types are supported.
Thanks for your help.

Answer 1

I finally got it to work like this
var _query = _dataContext.IndexLogs.GroupBy(l => l.InstrumentId, l => l)
.Select(grp => new { Id = grp.Key, Date = grp.Max(g => g.ActionDate) });
//Prequery to find log records that match given type and action type
var _indexes = _dataContext.IndexLogs.Where(l => l.Action == type
&& _query.Contains(new { Id = l.InstrumentId, Date = l.ActionDate})).Select(i => i.InstrumentId);
var _states = _dataContext.AdvancedIndexes
.Include(i => i.County.State)
.Where(a => a.Id > 0 && _indexes.Contains(a.Id))
.GroupBy(i => new { i.County.State.Id, i.County.State.Name })
.Select(g => new { fips = g.Key.Id, name = g.Key.Name, count = g.Count() });