CODEWITHSUNDEEP
c#performanceentity-frameworklinqif-statement
Ramesh Rajendran
Ramesh Rajendran

Reputation: 38683

Difference between && and where condition in entity framework query

Difference between and condition and two where condition in entity framework query

Code 1

I have using two where condition in my query

 dbContext.Projects.Where(p=>p.ProjectId!=ProjectId).Where(p=>p.Name==Name)
 .SingleOrDefault();

code 2

I have using && condition without using two where condition 

  dbContext.Projects.Where(p=>p.ProjectId!=ProjectId &&  
  p.Name==Name).SingleOrDefault();

The both queries are return same value. but i don't know the differences. Please explain to me, which one is better. and why?

Upvotes: 7

Views: 15058

Answers (3)

Abhishek
Abhishek

Reputation: 7045

Both queries are same. But Query 2 will give you better performance, as && will help you in short-circuit. In the first query, first where will yield the result and that will be given to 2nd where clause and then it will evaluate result based on the input. Let me know if you need more info.

Upvotes: 1

Michael Mairegger
Michael Mairegger

Reputation: 7301

If you open your query in LinqPad you will see that both queries

dbContext.Projects.Where(p=>p.ProjectId!=ProjectId).Where(p=>p.Name==Name)

dbContext.Projects.Where(p=>p.ProjectId!=ProjectId && p.Name==Name);

will result both in 

SELECT [...]
FROM [...]
WHERE p.ProjectId <> someId AND p.Name = 'something'

There is no difference neither in performance nor in SQL query structure.

Upvotes: 11

Mario The Spoon
Mario The Spoon

Reputation: 4859

From the documentation

Return value:

An IEnumerable that contains elements from the input sequence that satisfy the condition.

So the second where will only be applied to the records surviging the first where - which is identical to the && expression you built in code 2.

See: https://msdn.microsoft.com/de-de/library/bb534803%28v=vs.110%29.aspx

Upvotes: 3

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