Linq to SQL: How to create where IN clause

admin — Mon, 28 Feb 2011 08:55:07 +0000

int[] productList = new int[] { 1, 2, 3, 4 };

var myProducts = from p in db.Products
where productList.Contains(p.ProductID)
select p;

SELECT [t0].[ProductID], [t0].[Name], [t0].[ProductNumber], [t0].[MakeFlag], [t0].[FinishedGoodsFlag],
[t0].[Color], [t0].[SafetyStockLevel], [t0].[ReorderPoint], [t0].[StandardCost], [t0].[ListPrice],
[t0].[Size], [t0].[SizeUnitMeasureCode], [t0].[WeightUnitMeasureCode], [t0].[Weight], [t0].[DaysToManufacture],
[t0].[ProductLine], [t0].[Class], [t0].[Style], [t0].[ProductSubcategoryID], [t0].[ProductModelID],
[t0].[SellStartDate], [t0].[SellEndDate], [t0].[DiscontinuedDate], [t0].[rowguid], [t0].[ModifiedDate]
FROM [Production].[Product] AS [t0]
WHERE [t0].[ProductID] IN (@p0, @p1, @p2, @p3)

Source

Linq Exception(NullReferenceException): Object reference not set to an instance of an object

admin — Fri, 24 Sep 2010 05:35:36 +0000

With NullReferenceException:

Dim obj As DemographicProperties = Me
Dim m As IEnumerable(Of DemographicProperty) = From c In obj _
Where (c.MapClass.MapClassID = MapClassID) _
Order By c.Name Ascending _
Select c

If you are getting NullReferenceException, it means the MapClassID is null(nothing in vb.net)

Solve:

Dim obj As DemographicProperties = Me
Dim m As IEnumerable(Of DemographicProperty) = From c In obj _
Where ((Not c.MapClass Is Nothing) AndAlso (c.MapClass.MapClassID = MapClassID)) _
Order By c.Name Ascending _
Select c

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Linq to SQL: How to create where IN clause

Linq Exception(NullReferenceException): Object reference not set to an instance of an object