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Answer 1

+2 A:

var incident in new DataAccess.IncidentRepository().GetItems().Where(
                    i => i.IncidentDate >= startDate 
                    && i.IncidentDate <= endDate 
                    && i.ShiftId == shiftId 
                    && i.ProcessAreaId == processAreaId
                    && (plantId == null || i.PlantId == plantId)))

Alternatively, you could:

var incidents = new DataAccess.IncidentRepository().GetItems().Where(
                    i => i.IncidentDate >= startDate 
                    && i.IncidentDate <= endDate 
                    && i.ShiftId == shiftId 
                    && i.ProcessAreaId == processAreaId));

if (plantId != null)
    incidents = incidents.Where(i => i.PlantId == plantId);

foreach (var incident in incidents) {
   // ...
}

Mehrdad Afshari 2009-05-20 08:24:24

That makes no sense i.PlantId comes for the database plantId is the parameter passed into the method.

2009-05-20 08:25:59

so basicly if plantId == null then i.PlantId should not be added to the where clause.

2009-05-20 08:26:31

I dont think this will work.

2009-05-20 08:28:57

I added that option too. Both are effectively the same. Refresh to see.

Mehrdad Afshari 2009-05-20 08:29:02

in SQL I would do thisWHERE USerId = ISNULL(@UserId,UserId)

2009-05-20 08:29:46

It should work. There's no problem in chaining Where clauses. They act like AND.

Mehrdad Afshari 2009-05-20 08:30:05

+1 for converting common SQL dynamic parameter "trick" into Linq. ;)

J. Steen 2009-05-20 08:30:28

Thats where the problem comes in I will need to have like 50 if statements which is not what I wanted to do. I tought there might be a easy way

2009-05-20 08:30:52

The first query is effectively like your `ISNULL` query. The second doesn't send the parameter to the server at all if it's null.

Mehrdad Afshari 2009-05-20 08:31:09

So choose the first option. It's the most succinct way out there.

Mehrdad Afshari 2009-05-20 08:32:34

Answer 2

A:

var incident in new DataAccess.IncidentRepository().GetItems().Where(
                    i => i.IncidentDate >= startDate 
                    && i.IncidentDate <= endDate 
                    && i.ShiftId == shiftId 
                    && i.ProcessAreaId == processAreaId
                    && object.Equals(i.PlantId, plantId)))

crowleym 2009-05-20 08:35:33

It's not what the OP wants...

Mehrdad Afshari 2009-05-20 08:39:56

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Linq2SQL check if item is null

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