Category: LINQ

11 Aug 2014 01:45

Joined:	11/08/2014
Level:	Bronze
Points:	10

Points:	3

LINQ Single vs SingleOrDefault vs First vs FirstOrDefault

Many people get confused about the difference between Single, SingleOrDefault, First, and FirstOrDefault methods in Linq. Below is a chart explaining the difference between them and examples of each scenario.

Refer this link:

http://www.technicaloverload.com/linq-single-vs-singleordefault-vs-first-vs-firstordefault/

#749096

11 Aug 2014 02:27

Joined:	28/04/2006
Level:	Gold
Points:	29773

Points:	4

Hai Uday,
There is slight differences between these methods of LINQ. Below are the explanation of each one:
1. Single - This method in the Linq expression can be used when you are sure that there must be a single record will be the result for the query. It will throw error when single record is not as the result.
2. SingleOrDefault- This method can be used when you are sure that there might be maximum one record as the result. There could be no record or maximum one record.
3. First- This method of the Linq expression can be used when you are not sure about the results but you want the first record irrespective of the number of the records returns. There must be one record exists as the result set.
4. FirstOrDefault- The similar way, irrespective of the number of records as the result set, it will pick only the first record as the result. There could be no record then null will be returned.
Hope it will be helpful to you.

Regards,
Pawan Awasthi(DNS MVM)
+91 8123489140 (whatsApp), +60 14365 1476(Malaysia)
pawansoftit@gmail.com

#749097

11 Aug 2014 02:36

Joined:	18/07/2014
Level:	Gold
Points:	1837

Points:	4

Hello Uday,

You should search in google regarding that there are so many results over there ,eben in your reference link you can easily get idea regarding those all.
I gave you some references for your clear idea, just take a look.

1) Single searches for single instances. It is found in System.Linq. With it, we search a collection for a single instance of an element matching a condition. If the collection has any number other than one element, we get an exception.

Reference
http://www.dotnetperls.com/single

2) The SingleOrDefault() method returns a single specific element of a sequence or default value if that element is not found in the sequence. Whenever you use SingleOrDefault, you clearly state that the query should result in at most a single result

Reference
http://www.c-sharpcorner.com/UploadFile/3d39b4/singleordefault-and-firstordefault-methods-in-linq-to-sql/

3) First locates the first matching object. These objects can be of any type. We access the First extension method in the System.Linq namespace. The argument to First is a Predicate instance—it can be specified in the lambda syntax.

Reference
http://www.dotnetperls.com/first

4) FirstOrDefault is almost the same as First. The difference is how it handles empty collections. If a collection is empty, it returns the default value for the type. This method simplifies code. In some programs it eliminates exceptions.

Reference
http://www.dotnetperls.com/firstordefault

Regards,
Nirav Prabtani (Senior Web Developer)
Email : niravjprabtani@gmail.com
blog : niravprabtani.blogspot.in

#749268

13 Aug 2014 21:28

Joined:	05/11/2013
Level:	Gold
Points:	1551

Points:	3

Hi Uday,
please see the difference between Single, SingleOrDefault, First, and FirstOrDefault methods in Linq as below-

Single(): This method searches for single instances in a collection which matching a condition. If the collection has 0 or more than one matching element, we get an exception.

SingleOrDefault():This method returns
a single, specific element in a collection, or a default value if that element
is not found. If there is no matching element found then by default, it will return null values.

First()-This
method locates the first matching element in a collection. If the collection
has no matching element, we get an exception.

FirstOrDefault():This
method is almost the same as First. The difference is how it handles empty
collections. If a collection is empty, it returns the default value for the
type. This method eliminates the exceptions.

Thanks,
Ashutosh Jha
http://tricksroad.com

#749472

18 Aug 2014 05:59

Joined:	11/08/2014
Level:	Bronze
Points:	10

Points:	1

Hi Ashutosh Jha ,
Thank you for your valuable information

#749473

18 Aug 2014 06:00

Joined:	11/08/2014
Level:	Bronze
Points:	10

Points:	1

Hi Pawan,
Thank you for reply this post

#760128

30 Jun 2015 02:42

Joined:	29/10/2014
Level:	Gold
Points:	1106

Points:	3

Hi All,

if u want really know about the concept of Single or SinngleOrDefault() then u definitely follow the site there u get the best solutions alnog with best examples are there..

http://www.technicaloverload.com/linq-single-vs-singleordefault-vs-first-vs-firstordefault/

Thnaks a lot,
Chitaranjan

LINQ Single vs SingleOrDefault vs First vs FirstOrDefault

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