The call to Compile gets stripped out entirely by a special wrapper that was created by calling AsExpandable, and substituted for a correct expression tree. Of course, if this method actually ran, we'd end up with compiled IL code instead of an expression tree, and LINQ to SQL or Entity Framework would throw an exception
The anonymous function does not have any intrinsic type associated with it, although implicit conversion is possible for any delegate type as long as the parameters and return type are compatible. The exception to the parenthesis rule is that if the compiler can infer the data type and there is only a single input parameter, the statement lambda does not require parentheses (see Listing 12.17)
The Standard LINQ Operators
Set Operations The set operators in LINQ include Distinct (to remove duplicate values), Except (returns the difference of two sequences), Intersect (returns the intersection of two sequences), and Union (returns the unique elements from two sequences). The second parameter represents all the employees that matched the join criteria for this department (and it could be empty, as in the case of Skunkworks)
Introduction To LINQ
As an example, let's imagine we need to get a list of all the svchost.exe processes running on a machine and return them sorted according to their working set. The deep integration of LINQ into .NET languages and tools allows developers to be more productive and work at a higher level of abstraction when creating data oriented applications
Just run it by VS2008 Express i had all examples by different implementation of linq, like: - Linq To Sql - Linq to XML - Linq over DataSet - XQury use cases Great! LukCAD - Tuesday, January 8, 2008 7:46:45 AM Great! So why is this a zip somewhere on MSDN that has a code file we need to compile? If this works as good as you say it does, please consider putting it in the Extensions release. Dave - Sunday, February 3, 2008 1:12:49 PM How can you handle null values with the LINQ data source control? For example I have a drop down list that controls the data displayed in a gridview
The generic forms are used most often when you write queries directly in the programming language and perform better since we can avoid using reflection to construct instances. However, instead of just posting a full sample here I felt it prudent to go step by step so I can actual dive deep and explain everything that is going on instead of just dumping it all in your lap and letting you find your own way
-Fahad Fahad - Tuesday, April 22, 2008 10:14:20 AM Not sure, why you need it, i am curious to know what is your objective that can not be accomplished with existing solution. Hope this helps, mehfuzh - Friday, February 15, 2008 7:32:06 PM Hi Mehfuz, Is there any way to generate expression for LINQ on objects??, my app is full of objects which i would process it thru reflection, the LINQ to SQL works like a charm for me, but i would also like to add this feature in my app with LINQ on objects
Given this code, the library function calls (like Where and Select in case of LINQ) can consume that expression tree to analyze the code the user wrote, extracting the intent and turning it into execution in whatever way is right for the task at hand (e.g. Typical sample is the use of expression trees in LINQ where nonsense queries can be written, in a sense they cannot be remoted to the target query language
The article describes how to implement a LINQ provider for NHibernate, so it is beneficial if you know the Hibernate Query Language (HQL); however, due to the syntactic similarity of HQL to SQL, the principles shown in the sample can easily be translated into using re-linq to implement a SQL LINQ provider instead (even most of the code will be identical). The TDD developed open source re-motion framework supplies a commercial class LINQ provider library in the form of its re-linq component, that transforms the abstract syntax tree back to an object model that represents the LINQ query expression in a form much closer to typical query languages (In fact, re-linq can even transform hand-made abstract syntax trees into a semantically identical representation in query expression syntax)
We can use a looping method, where we have to look at the price value of each object in the list one-by-one and then retrieve the objects that have less value for the Price property. TakeWhile() uses an expression to include the elements in the collection as long as the condition is true and it ignores the other elements in the list
example....I have seen this solution before, but, in the first place, how was Int...but data grid view i can.t add rows and i can.t edit in any cells? ...This broke down when I tried to use it in multiple places
I scratched my head a bit and then remembered a long-lost sample for dynamically building LINQ queries written back when the original Visual Studio 2008 shipped. Scott provides a nice overview of the Dynamic Data architecture and then gets his hands dirty with some custom filters using the advanced capabilities available in Dynamic Data Futures
LINQ Introduction Part 1 Of 3 - CodeProject
It then enumerates the source sequence, repeatedly computing the next accumulator value by invoking the specified function with the current accumulator value as the first argument and the current sequence element as the second argument. Also if we had some complicated nested, joined, aggregate (SUM, COUNT) type operators as part of the query, it might be quite a complex type that we have to declare as a return type
When and why would you use this? From the LINQ expressions I've seen that have them, they just seem to wrap existing expressions without adding any value
As with every piece of technology at our fingertips, LINQ can and will be abused and misused alike, and the ability to distinguish between that, and proper usage, is only dependent on one thing: knowledge. Advantage of Lambda Lambda will have an advantage since it creates a delegate and by using the delagte you can just pass the input paremeters and get the result for the different input parameters.You need not write different queries for different criteria as well
Duncan Ady Admin 565 posts Posted 13 Sep 2011 Link to this post Hello Duncan, It seems that like u.UserGroups is a single object and the from clause expects a sequence of objects
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