What is SelectMany in C#?

The SelectMany() method is used to “flatten” a sequence in which each of the elements of the sequence is a separate, subordinate sequence.

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Can SelectMany return null?

@flem They can never be null because that’s how Where and SelectMany work. If the input is null they throw an exception, and if it’s not null the result will either be a sequence of items, or an empty sequence.

How do you use AsEnumerable?

AsEnumerable() in C# To cast a specific type to its IEnumerable equivalent, use the AsEnumerable() method. It is an extension method. int[] arr = new int[5]; arr[0] = 10; arr[1] = 20; arr[2] = 30; arr[3] = 40; arr[4] = 50; Now, get the IEnumerable equivalent.

How do I check DBNull in LINQ query?

The above code is giving a compilation error like “cannot be applied to operands of type ‘string’ to ‘System.DBNull’
Then it’s probably the amount field.
string amount= obj.currency == DBNull.Value? “” :
I think the syntax is String sCurr = (object)obj.currency == DBNull.Value? “” :
You should remove the DBNull.

How do you check if a list is empty in LINQ?

Check if a list is empty in C#

Using Enumerable. Any() method ( System. Linq )
Using Enumerable.FirstOrDefault() method ( System.Linq ) The Enumerable.FirstOrDefault() method returns the first element of a sequence.
Using Enumerable. Count() method ( System.

Why we use IQueryable in LINQ?

IQueryable is suitable for querying data from out-memory (like remote database, service) collections. While querying data from a database, IQueryable executes a “select query” on server-side with all filters. IQueryable is beneficial for LINQ to SQL queries.

What is difference between single and SingleOrDefault in Linq?

Use Single() when you are sure that the query must return only one record, and use SingleOrDefault() when a query returns the only element from the sequence, or a default value if the sequence is empty.

How do you check if a list is empty or not in C#?

Now to check whether a list is empty or not, use the Count property. if (subjects. Count == 0) Console.