LINQ to SQL refactoring foreach help - linq-to-sql

Question

Can this be refactored into one LINQ statement? I feel like it can be but can't wrap my head around it. The mishmash of extension methods and LINQ just looks ugly to me.
(db is a DataContext.)
void AddToSeries(Series series, DateTime date)
{
foreach (var date in db.Ad.Select(ad => ad.DateTime.Date).Distinct())
{
var phraseCount = (from pc in db.PhraseCount
where pc.DateTime.Date == date
select pc.Count).SingleOrDefault();
var adCount = db.Ad.Where(ad => ad.DateTime.Date == date).Count();
series.Add(new KeyValuePair<DateTime, double>(date, adCount));
}
}

Answer 1

First refactor to consistent style.
void AddToSeries(Series series, DateTime date)
{
var dates = db.Ad
.Select(ad => ad.DateTime.Date)
.Distinct();
foreach (DateTime date in dates)
{
var phraseCount = db.PhraseCount
.Where(pc => pc.DateTime.Date == date)
.Select(pc => pc.Count)
.SingleOrDefault();
var adCount = db.Ad
.Where(ad => ad.DateTime.Date == date)
.Count();
series.Add(new KeyValuePair<DateTime, double>(date, adCount));
}
}
Aha:
phraseCount is not used
key is a date, value is a count
multiple database trips is no fun
date parameter for this method is blocked by the foreach variable
Now we can refactor:
void AddToSeries(Series series, DateTime date)
{
var pairs = db.Ad
.GroupBy(ad => ad.DateTime.Date)
.Select(g => new {key = g.Key, theCount = g.Count()});
foreach (var x in pairs)
{
series.Add(new KeyValuePair<DateTime, double>(x.key, x.theCount));
}
}