Basic SQL count with LINQ

I have a trivial issue that I can't resolve. Currently our app uses Linq to retrieve data and get a basic integer value of the row count. I can't form a query that gives back a count without a 'select i'. I don't need the select, just the count(*) response. How do I do this? Below is a sample:

return (from io in db._Owners
           where io.Id == Id && io.userId == userId
  开发者_高级运维         join i in db._Instances on io.Id equals i.Id **select i**).Count()

;

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The select i is fine - it's not actually going to be fetching any data back to the client, because the Count() call will be translated into a Count(something) call at the SQL side.

When in doubt, look at the SQL that's being generated for your query, e.g. with the DataContext.Log property.

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Using the LINQ query syntax requires a select statement. There's no way around that.

That being said, the statement will get transformed into a COUNT()-based query; the select i is there only to satisfy the expression system that underlies the LINQ query providers (otherwise the type of the expression would be unknown).

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Including the select will not affect the performance here because the final query will get translated into SQL. At this point it will be optimized and will be like select (*) from ......