EF6 Generated SQL

GeneratedSql.sql

SELECT TOP (4) 
    [Project1].[ProductID] AS [ProductID],
    [Project1].[Name] AS [Name], 
    [Project1].[Description] AS [Description], 
    [Project1].[Price] AS [Price], 
    [Project1].[Category] AS [Category]
    FROM ( SELECT [Project1].[ProductID] AS [ProductID], [Project1].[Name] AS [Name], [Project1].[Description] AS [Description], [Project1].[Price] AS [Price], [Project1].[Category] AS [Category], row_number() OVER (ORDER BY [Project1].[ProductID] ASC) AS [row_number]
        FROM ( SELECT 
            [Extent1].[ProductID] AS [ProductID], 
            [Extent1].[Name] AS [Name], 
            [Extent1].[Description] AS [Description], 
            [Extent1].[Price] AS [Price], 
            [Extent1].[Category] AS [Category]
            FROM [dbo].[Products] AS [Extent1]
            WHERE ('NULL' /* @p__linq__0 */ IS NULL) OR ([Extent1].[Category] = 'NULL' /* @p__linq__1 */) OR (([Extent1].[Category] IS NULL) AND ('NULL' /* @p__linq__1 */ IS NULL))
        )  AS [Project1]
    )  AS [Project1]
    WHERE [Project1].[row_number] > 0
    ORDER BY [Project1].[ProductID] ASC

SimpleQuery.cs

public void Query(string category = null)
{
          // If the category parameter is null, we want to get all Products.
          // If a category is passed in, we want to get only the Products in that category.
          repository.Products
                    .Where(p => category == null || p.Category == category)
                    .OrderBy(p => p.ProductID)
                    .Skip(0)
                    .Take(4)
}