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c#linqoptimizationlinq-to-sqlsum
Markus Werner
Markus Werner

Reputation: 109

How can i optimize this linq function for calculating sum of "OrePreviste"?

the tableis this:

Table

The function in linq is this:

 public int CalcolaOreOccupate(string data)
    {
        int oreOccupate = 0;

        if (String.IsNullOrEmpty(data))
        {
            using (DatabaseDataContext contestoDB = new DatabaseDataContext())
            {
                contestoDB.ObjectTrackingEnabled = false;

                var elencoOre = (from db in contestoDB.Eventi
                                 where db.DataPrenotazione.Date == DateTime.Now.Date
                                 select db);

                foreach (var o in elencoOre)
                {
                    oreOccupate += o.OrePreviste;
                }
            }

        }
        else
        {
              /* ... othere code ... */
        }

        return oreOccupate;
    }

oreOccupate is sum of OrePreviste. I wanna get better function of mine. How can i do with linq? Thanks

Upvotes: 3

Views: 359

Answers (1)

teo van kot
teo van kot

Reputation: 12491

Just use Sum() extension method:

var nowDate = DateTime.Now.Date; 
oreOccupate = contestoDB.Eventi
           .Where(x => x.DataPrenotazione.Date == nowDate)
           .Select(x => x.OrePreviste)
           .DefaultIfEmpty(0)
           .Sum();

When you do it like you show you basically get all your data from DB to your server to process and if you using MS SQL you can translate your query like i show to make all calculations in your Data base using LinqToSQL

As @enigmativity point in comments there is no need to init DateTime.Now.Date in separate variable since you using linqtosql and it will be translated to sql statement so called just once.

Upvotes: 4

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