I have an Entity Framework 4.0 Entity Object called Revision w/ Nullable DateEffectiveFrom and DateEffectiveTo dates. I was wondering if there was a short-hand way of querying an object's RevisionHistory based on a particular QueryDate date instead of having to use the following query structure:

var results = EntityObject.Revisions.Where(x =>
    (x.DateEffectiveFrom == null && x.DateEffectiveTo == null) ||
    (x.DateEffectiveFrom == null && x.DateEffectiveTo >= QueryDate) ||
    (x.DateEffectiveFrom <= QueryDate && x.DateEffectiveTo == null) ||
    (x.DateEffectiveFrom <= QueryDate && x.DateEffectiveTo >= QueryDate));

I've tried creating the following boolean function in the Revision class:

partial class Revision
{
    public bool IsEffectiveOn(DateTime date)
    {
        return (x.DateEffectiveFrom == null && x.DateEffectiveTo == null) ||
            (x.DateEffectiveFrom == null && x.DateEffectiveTo >= date) ||
            (x.DateEffectiveFrom <= date && x.DateEffectiveTo == null) ||
            (x.DateEffectiveFrom <= date && x.DateEffectiveTo >= date));
    }
    ...
}

And then updating the query to:

var results = EntityObject.Revisions.Where(x => x.IsEffectiveOn(QueryDate));

but this obviously doesn't translate to SQL. Any ideas would be much appreciated.