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  • Translate SQL to LINQ query - group/join/filter

    - by Paddy
    I have the following query: SELECT S.[FlowOrder], S.[DESCRIPTION], COUNT(I.ID) FROM WorkFlowStatus AS S INNER JOIN Item AS I ON S.ID = I.StatusID WHERE I.Installation = '1' GROUP BY S.[Description], S.[FlowOrder] ORDER BY S.[FlowOrder] Which gives me the count of an item, grouped by a foreign key to workflow, outputting the descriptive name from my FK table. I've go this far with the LINQ query (using LINQ-to-SQL) in the background: var items = from s in _entities.WorkflowStatus join i in _entities.Items on s.ID equals i.StatusId into Statuses orderby s.FlowOrder select new {s.Description, ItemCount = Statuses.Count() }; How do I get the where clause in the SQL into this LINQ query?

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  • How do I generate optimized SQL with my (added) partial methods on LINQ entities

    - by Ra
    Let's say I have a Person table with a FirstName and LastName column. I extended the Person LINQ entity class with a get property "FullName", that concatenates the first and last names. A LINQ query like: from person... select fullName where id = x generates SQL selecting all Patient columns, since FullName is evaluated after firing the query. I would like to limit the select clause to only the 2 columns required. This is a simple example, but the limitation it shows is that I cannot isolate my business/formatting rules but have to embed them in the LINQ query, so they're not reusable (since it is in the select part) or I need select both columns separately, and then concatenate them higher up in the data or business layer with static helper methods. Any ideas for a clean design using the entity partial classes or extensions? Thanks

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  • Comparing 2 linq applications: Unexpected result

    - by lukesky
    I drafted 2 ASP.NET applications using LINQ. One connects to MS SQL Server, another to some proprietary memory structure. Both applications work with tables of 3 int fields, having 500 000 records (the memory structure is identical to SQL Server table). The controls used are regular: GridView and ObjectDataSource. In the applications I calculate the average time needed for each paging click processing. LINQ + MS SQL application demands 0.1 sec per page change. LINQ + Memory Structure demands 0.8 sec per page change. This Is shocking result. Why the application handling data in memory works 8 times slower than the application using hard drive? Can anybody tell me why that happens?

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  • Linq query with Array in where clause?

    - by Matt Dell
    I have searched for this, but still can't seem to get this to work for me. I have an array of Id's associated with a user (their Organization Id). These are placed in an int[] as follows: int[] OrgIds = (from oh in this.Database.OrganizationsHierarchies join o in this.Database.Organizations on oh.OrganizationsId equals o.Id where (oh.Hierarchy.Contains(@OrgId)) || (oh.OrganizationsId == Id) select o.Id).ToArray(); The code there isn't very important, but it shows that I am getting an integer array from a Linq query. From this, though, I want to run another Linq query that gets a list of Personnel, that code is as follows: List<Personnel> query = (from p in this.Database.Personnels where (search the array) select p).ToList(); I want to add in the where clause a way to select only the users with the OrganizationId's in the array. So, in SQL where I would do something like "where OrganizationId = '12' or OrganizationId = '13' or OrganizatonId = '17'." Can I do this fairly easily in Linq / .NET?

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  • linq with Include and criteria

    - by JMarsch
    How would I translate this into LINQ? Say I have A parent table (Say, customers), and child (addresses). I want to return all of the Parents who have addresses in California, and just the california address. (but I want to do it in LINQ and get an object graph of Entity objects) Here's the old fashioned way: SELECT c.blah, a.blah FROM Customer c INNER JOIN Address a on c.CustomerId = a.CustomerId where a.State = 'CA' The problem I'm having with LINQ is that i need an object graph of concrete Entity types (and it can't be lazy loaded. Here's what I've tried so far: // this one doesn't filter the addresses -- I get the right customers, but I get all of their addresses, and not just the CA address object. from c in Customer.Include(c = c.Addresses) where c.Addresses.Any(a = a.State == "CA") select c // this one seems to work, but the Addresses collection on Customers is always null from c in Customer.Include(c = c.Addresses) from a in c.Addresses where a.State == "CA" select c; Any ideas?

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  • LINQ Except operator and object equality

    - by Abhijeet Patel
    Here is an interesting issue I noticed when using the Except Operator: I have list of users from which I want to exclude some users: The list of users is coming from an XML file: The code goes like this: interface IUser { int ID { get; set; } string Name { get; set; } } class User: IUser { #region IUser Members public int ID { get; set; } public string Name { get; set; } #endregion public override string ToString() { return ID + ":" +Name; } public static IEnumerable<IUser> GetMatchingUsers(IEnumerable<IUser> users) { IEnumerable<IUser> localList = new List<User> { new User{ ID=4, Name="James"}, new User{ ID=5, Name="Tom"} }.OfType<IUser>(); var matches = from u in users join lu in localList on u.ID equals lu.ID select u; return matches; } } class Program { static void Main(string[] args) { XDocument doc = XDocument.Load("Users.xml"); IEnumerable<IUser> users = doc.Element("Users").Elements("User").Select (u => new User { ID = (int)u.Attribute("id"), Name = (string)u.Attribute("name") } ).OfType<IUser>(); //still a query, objects have not been materialized var matches = User.GetMatchingUsers(users); var excludes = users.Except(matches); // excludes should contain 6 users but here it contains 8 users } } When I call User.GetMatchingUsers(users) I get 2 matches as expected. The issue is that when I call users.Except(matches) The matching users are not being excluded at all! I am expecting 6 users ut "excludes" contains all 8 users instead. Since all I'm doing in GetMatchingUsers(IEnumerable users) is taking the IEnumerable and just returning the IUsers whose ID's match( 2 IUsers in this case), my understanding is that by default "Except" will use reference equality for comparing the objects to be excluded. Is this not how "Except" behaves? What is even more interesting is that if I materialize the objects using .ToList() and then get the matching users, and call "Except", everything works as expected! Like so: IEnumerable users = doc.Element("Users").Elements("User").Select (u = new User { ID = (int)u.Attribute("id"), Name = (string)u.Attribute("name") } ).OfType().ToList(); //explicity materializing all objects by calling ToList() var matches = User.GetMatchingUsers(users); var excludes = users.Except(matches); // excludes now contains 6 users as expected I don't see why I should need to materialize objects for calling "Except" given that its defined on IEnumerable? Any suggesstions / insights would be much appreciated.

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  • for vs. foreach vs. LINQ

    - by beccoblu
    When I write code in Visual Studio, ReSharper (God bless it!) often suggests me to change my old-school for loop in the more compact foreach form. And often, when I accept this change, ReSharper goes a step forward, and suggests me to change it again, in a shiny LINQ form. So, I wonder: are there some real advantages, in these improvements? In pretty simple code execution, I cannot see any speed boost (obviously), but I can see the code becoming less and less readable... So I wonder: is it worth it?

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  • Creating a Linq->HQL provider

    - by Mike Q
    Hi all, I have a client application that connects to a server. The server uses hibernate for persistence and querying so it has a set of annotated hibernate objects for persistence. The client sends HQL queries to the server and gets responses back. The client has an auto-generated set of objects that match the server hibernate objects for query results and basic persistence. I would like to support using Linq to query as well as Hql as it makes the queries typesafe and quicker to build (no more typos in HQL string queries). I've looked around at the following but I can't see how to get them to fit with what I have. NHibernate's Linq provider - requires using NHibernate ISession and ISessionFactory, which I don't have LinqExtender - requires a lot of annotations on the objects and extending a base type, too invasive What I really want is something that will generate give me a nice easy to process structure to build the HQL queries from. I've read most of a 15 page article written by one of the C# developers on how to create custom providers and it's pretty fraught, mainly because of the complexity of the expression tree. Can anyone suggest an approach for implementing Linq - HQL translation? Perhaps a library that will the cleanup of the expression tree into something more SQL/HQLish. I would like to support select/from/where/group by/order by/joins. Not too worried about subqueries.

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  • Help regarding database and logic layer for my ASP.NET MVC application

    - by Ismail S
    I'm going to start a new project which is going to be small initially but may grow to big over the years. I'm strongly convinced that I'm going to use ASP.NET MVC with jQuery for UI. I want to go for MySQL as database for some reasons but worried on few things. I've a good years of experience working on SQL Server databases and on one project I've had a bad experience creating and managing stored procedures on MySQL database. I'm totally new to Linq but I see that it is easier to use once you are familiar with it. First thing is that accessing data should be easy. So I thought I should use MySQL to Linq but somewhere I read that it is not directly supported but MySQL .NET connector adds support for EntityFramework. I don't know what are the pros and cons of it. I would love if I can implement repository pattern. Will it be possible if I use Entity Framework? I'm not clear on how I should go about all this or I should just forget every thing and directly use SQL to Linq on SQL Server. I'm also concerned about the performance. Someone told me that if we use Entity framework it fetches lot of data and then filter it. Is that right?

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  • Cutting objects and applying texture to cut. Unity3d/C#

    - by Timothy Williams
    Basically what I'm trying to do is figure out how to calculate realtime cutting of objects, and apply a texture to the cut. I found some good scripts, but most of them have been abandoned and aren't really fully working yet. Applying textures: http://forum.unity3d.com/threads/75949-Mesh-Real-Cutting?highlight=mesh+real+cutting Cutting: http://forum.unity3d.com/threads/78594-Object-Cutter Another (Free) Cutter (Also, I'm not entirely sure how this one will handle cutting complex meshes): http://forum.unity3d.com/threads/69992-fake-slicer?p=449114&viewfull=1#post449114 My plan as of right now is to combine links 1 & 2 or 1 & 3 programming wise. What I'm asking here for is any advice on how to advance (links to asset store packages, or other codes to show how to accomplish something complex like this.)

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  • NHibernate Linq Timeout

    - by DarrenMcD
    How do I increase the timeout in NHibernate Linq To Sql? Not the Connection Timeout but the ado command timeout. using (ISession session = NHibernateHelper.OpenSession(NHibernateHelper.Databases.CarrierCDR)) using (session.BeginTransaction(IsolationLevel.ReadUncommitted)) { lCdrs = (from verizon in session.Linq<Domain.Verizon>() where verizon.Research == true && verizon.ReferenceTable == null orderby verizon.CallBillingDate descending select verizon).ToList(); }

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  • LINQ to XML vs. XmlReader

    - by Vadim
    In my Silverlight application I'm using mostly XmlReader but I'm playing with idea to replace XmlReader implementation with LINQ to XML. What are pros and cons between LINQ to XML and XmlReader in Silverlight?

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  • "Push" linq vs reactive framework

    - by Benjol
    (Once again exposing the depths of my ignorance here by combining two concepts which I haven't grokked) I read here about the Reactive framework being a 'Push' model compared to Linq's 'Pull' model. This reminded me of reading an article about 'Push' Linq. Is there really any similarity between these two 'frameworks'? UPDATE Since I asked this question, Jon Skeet has asked it too, here are his first and second impressions.

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  • mysql and linq support

    - by darko petreski
    Hi All, I have read in many forums that there is no good linq for mysql (free) but his forums are 2 years old. In the meantime is there any good free linq for mysql ? Hog good is for professional use? Regards

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  • LINQ and Storedprocedure

    - by Amutha
    The interview i faced was "What is the difference between LINQ and Stored procedure?". I don't know whether it is a vague question or proper one. I answered "In Linq there is a support for Closure so you can refer the value of outer parameter inside the anonymous body,you can't do the same with Stored procedure". Just i am requesting you the proper answer.

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  • Xml.Linq library in Silverlight 3.0

    - by Jayesh
    Hi, I am working on a Silverlight 3.0 application I have added a reference to the System.Xml.linq dll. I can also can see it in the references folder of my Silverlight app. however when I try to use it [using System.Xml.linq] it says are you missing an assembly reference! I am stumped! Please help

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  • Simple database design and LINQ

    - by Anders Svensson
    I have very little experience designing databases, and now I want to create a very simple database that does the same thing I have previously had in xml. Here's the xml: <services> <service type="writing"> <small>125</small> <medium>100</medium> <large>60</large> <xlarge>30</xlarge> </service> <service type="analysis"> <small>56</small> <medium>104</medium> <large>200</large> <xlarge>250</xlarge> </service> </services> Now, I wanted to create the same thing in a SQL database, and started doing this ( hope this formats ok, but you'll get the gist, four columns and two rows): > ServiceType Small Medium Large > > Writing 125 100 60 > > Analysis 56 104 200 This didn't work too well, since I then wanted to use LINQ to select, say, the Large value for Writing (60). But I couldn't use LINQ for this (as far as I know) and use a variable for the size (see parameters in the method below). I could only do that if I had a column like "Size" where Small, Medium, and Large would be the values. But that doesn't feel right either, because then I would get several rows with ServiceType = Writing (3 in this case, one for each size), and the same for Analysis. And if I were to add more servicetypes I would have to do the same. Simply repetitive... Is there any smart way to do this using relationships or something? Using the second design above (although not good), I could use the following LINQ to select a value with parameters sent to the method: protected int GetHourRateDB(string serviceType, Size size) { CalculatorLinqDataContext context = new CalculatorLinqDataContext(); var data = (from calculatorData in context.CalculatorDatas where calculatorData.Service == serviceType && calculatorData.Size == size.ToString() select calculatorData).Single(); return data.Hours; } But if there is another better design, could you please also describe how to do the same selection using LINQ with that design? Please keep in mind that I am a rookie at database design, so please be as explicit and pedagogical as possible :-) Thanks! Anders

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  • Linq to Entities and outer joins issue

    - by Robert Koritnik
    Can somebody tell me, why does Linq to Entities translate many to 1 relationships to left outer joins instead of inner joins? It relation was many to 0..1. There's referential constraint on DB itself, that ensures there's a record in the right table, so inner join should be used instead. Is it possible to write LINQ in a way so they will translate to inner joins rather than left outer joins. It would speed query execution a lot.

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  • Retrieve data using Dynamic Query and Linq to SQL

    - by GigaPr
    Hi I have a really complicated dynamic query that i want to use to retrieve data from the database I am working in .net 3.5 sql server 2008 i created a stored procedure that accepts a varchar(max) as input parameter and does execute (@SqlQuery) it executes but does not return anything I really would like to use LINQ as all my project is implemented using linq Any Idea how to do it what is the problem?

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  • Setting SQL Relationships For LINQ Queries

    - by Soo
    I have two tables that I'm trying to create a relationship between so I can write nice LINQ queries that don't require join. Widgets WidgetId WidgetDescription Orders OrderId WidgetId OrderDate What I want to be able to do is create a LINQ query that does something similar to: var result = from x in db.Widgets Where x.Orders.OrderDate == "5/11/2010" select x; I can't seem to get intellitext to pick up the other database despite creating a relationship in SQL server. Are there any additional steps I need to take to make this work?

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  • how to create a linq query using join and max

    - by geoff swartz
    I have 2 tables in my linq dbml. One is people with a uniqueid called peopleid and the other is a vertical with a foreign key for peopleid and a uniqueid called id. I need to create a type of linq query that does a left outer join on people and gets the latest record in the vertical table based off the max(id) column. Can anyone suggest what this should look like? Thanks.

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