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In LINQ, what is the main difference / usefulness between .Any <> and .Where <> to check if there are records

For example, if I had a Linq to SQL data context or I had ADO.NET Entity Framework entities mapped to a database table and I want to test one client ...

Is there a big difference between:

MyDatabaseContext.Customers.Any(c => c.CustomerId == 3)

and

MyDatabaseContext.Customers.Where(c => c.CustomerId == 3)

.Any <> - the return type bool

.Where <> - the return type of the IQueryable

EDIT: Corrected question wording after accepting answer from Fredrik Mörk - thanks.

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5 answers


Check the documentation again:



There might be a performance difference in that it Any

stops as soon as it can determine the result (when it finds a matching element), and Where

must always loop through all the elements before returning the result. So if you only need to check if there are matching items, it Any

would be a set method.

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Any

returns a bool

, but Where

returns IQueryable

. If you are lazy, you can expect Any

to complete as soon as one satisfying item is found (return true), and Where

will search for all of them.



If you want to pick one client, Single

this is what you are looking for.

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Any()

returns bool. That is, are there any items that match the condition. Use Any()

it if you just want to know if you have items to work with. For example. prefer Any()

over Count() == 0

, for example, as the latter can enumerate the entire sequence to see if it is empty or not.

Where()

returns a sequence of elements that match a condition.

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Any<>

checks if any elements meet the criteria, i.e. returns bool

, which means it only has to find the first element, which can be very fast. Whereas it Where<>

enumerates all the elements that meet the condition, which means it must iterate over the entire collection.

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Any tests lambda / predicate and returns true / false

Returns a set of objects for which the lambda / predicate is IQueryable

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