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  • How to use linq to find the minimum

    - by Danvil
    I have a class A { public float Score; ... } and a List<A> items and would like to find the A which has minimal score. Using items.Min(x => x.Score) gives the minimal score and not the instance with minimal score. How can I get the instance with only iterating once through my Collection?

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  • How to bind gridview using linq/Entity Framework?

    - by Kay
    I need to bind GridView, I am using this code: ProductDBEntities db = new ProductPDBEntities(); var pro = from u in db.Products where u.PID == 1 select u; if (pro != null) { GridView1.DataSource = pro; GridView1.DataBind(); } and getting this error. System.InvalidOperationException: Sequence contains more than one element Can somebody please tell me what am I doin wrong?

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  • linq expression in vb.net

    - by Thurein
    Hi, Can any body translate the following c# code to vb. I have tried telarik code converter but I got problem at expression.call and it won't compile at all. private static IOrderedQueryable<T> OrderingHelper<T>(IQueryable<T> source, string propertyName, bool descending, bool anotherLevel) { ParameterExpression param = Expression.Parameter(typeof(T), string.Empty); MemberExpression property = Expression.PropertyOrField(param, propertyName); LambdaExpression sort = Expression.Lambda(property, param); MethodCallExpression call = Expression.Call( typeof(Queryable), (!anotherLevel ? "OrderBy" : "ThenBy") + (descending ? "Descending" : string.Empty), new[] { typeof(T), property.Type }, // error line source.Expression, Expression.Quote(sort)); return (IOrderedQueryable<T>)source.Provider.CreateQuery<T>(call); } thanks Thurein

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  • Linq DateTime expressions wont compare if only one is nullable

    - by tigermain
    I have been getting the following exception: The binary operator GreaterThanOrEqual is not defined for the types 'System.Nullable`1[System.DateTime]' and 'System.DateTime'. I am getting the left hand expression from a class property which is a nullable datetime variable and my right hand side is using Expression.Constant(new Nullable<DateTime>(DateTime.Now)) However I still get the above exception despite explicitly setting the right hand expression to a nullable type

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  • LINQ to SQL: On load processing of lazy loaded associations

    - by Matt Holmes
    If I have an object that lazy loads an association with very large objects, is there a way I can do processing at the time the lazy load occurs? I thought I could use AssociateWith or LoadWith from DataLoadOptions, but there are very, very specific restrictions on what you can do in those. Basically I need to be notified when an EntitySet< decides it's time to load the associated object, so I can catch that event and do some processing on the loaded object. I don't want to simply walk through the EntitySet when I load the parent object, because that will force all the lazy loaded items to load (defeating the purpose of lazy loading entirely).

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  • Understanding #DAX Query Plans for #powerpivot and #tabular

    - by Marco Russo (SQLBI)
    Alberto Ferrari wrote a very interesting white paper about DAX query plans. We published it on a page where we'll gather articles and tools about DAX query plans: http://www.sqlbi.com/topics/query-plans/I reviewed the paper and this is the result of many months of study - we know that we just scratched the surface of this topic, also because we still don't have enough information about internal behavior of many of the operators contained in a query plan. However, by reading the paper you will start reading a query plan and you will understand how it works the optimization found by Chris Webb one month ago to the events-in-progress scenario. The white paper also contains a more optimized query (10 time faster), even if the performance depends on data distribution and the best choice really depends on the data you have. Now you should be curious enough to read the paper until the end, because the more optimized query is the last example in the paper!

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  • linq to sql loadwith vs associatewith

    - by stackoverflowuser
    what is the difference between loadwith and associatewith. From the articles i read it seems that loadwith is used to load addition data (eg all orders for the customers). While AssociateWith is used to filter data. Is that a correct understanding? Also it will be nice if someone can explain this with an example based explanation.

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  • LINQ to SQL: making a "double IN" query crashes

    - by Alex
    I need to do the following thing: var a = from c in DB.Customers where (from t1 in DB.Table1 where t1.Date >= DataTime.Now select t1.ID).Contains(c.ID) && (from t2 in DB.Table2 where t2.Date >= DataTime.Now select t2.ID).Contains(c.ID) select a It doesn't want to run. I get the following error: Timeout expired. The timeout period elapsed prior to completion of the operation or the server is not responding. But when I try to run var a = from c in DB.Customers where (from t1 in DB.Table1 where t1.Date >= DataTime.Now select t1.ID).Contains(c.ID) select a OR var a = from c in DB.Customers where (from t2 in DB.Table2 where t2.Date = DataTime.Now select t2.ID).Contains(c.ID) select a It works! I'm sure that there both IN queries contain some customers ids.

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  • Parallelizing some LINQ to XML

    - by Lol coder
    How can I make this code run in parallel? List<Crop> crops = new List<Crop>(); //Get up to 10 pages of data. for (int i = 1; i < 10; i++) { //i is basically used for paging. XDocument document = XDocument.Load(string.Format(url, i)); crops.AddRange(from c in document.Descendants("CropType") select new Crop { //The data here. }); }

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  • linq multiple order DESCENDING

    - by ile
    .OrderBy(y => y.Year).ThenBy(m => m.Month); How to set descending order? EDIT: I tried this: var result = (from dn in db.DealNotes where dn.DealID == dealID group dn by new { month = dn.Date.Month, year = dn.Date.Year } into date orderby date.Key.year descending orderby date.Key.month descending select new DealNoteDateListView { DisplayDate = date.Key.month + "-" + date.Key.year, Month = date.Key.month, Year = date.Key.year, Count = date.Count() }) //.OrderBy(y => y.Year).ThenBy(m => m.Month) ; And it seems working. Is it wrong to use orderby twice like I used it here?

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  • LINQ to Sql: Insert instead of Update

    - by Christina Mayers
    I am stuck with this problems for a long time now. Everything I try to do is insert a row in my DB if it's new information - if not update the existing one. I've updated many entities in my life before - but what's wrong with this code is beyond me (probably something pretty basic) I guess I can't see the wood for the trees... private Models.databaseDataContext db = new Models.databaseDataContext(); internal void StoreInformations(IEnumerable<EntityType> iEnumerable) { foreach (EntityType item in iEnumerable) { EntityType type = db.EntityType.Where(t => t.Room == item.Room).FirstOrDefault(); if (type == null) { db.EntityType.InsertOnSubmit(item); } else { type.Date = item.Date; type.LastUpdate = DateTime.Now(); type.End = item.End; } } } internal void Save() { db.SubmitChanges(); } Edit: just checked the ChangeSet, there are no updates only inserts. For now I've settled with foreach (EntityType item in iEnumerable) { EntityType type = db.EntityType.Where(t => t.Room == item.Room).FirstOrDefault(); if (type != null) { db.Exams.DeleteOnSubmit(type); } db.EntityType.InsertOnSubmit(item); } but I'd love to do updates and lose these unnecessary delete statements.

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  • LINQ, Left Join, Only Get where null in join table

    - by kmehta
    Hi. I am trying to do a left outer join on two tables, but I only want to return the results from the first table where the second table does not have a record (null). var agencies = from a in agencyList join aa in joinTable on a.AgencyId equals aa.AgencyId into joined from aa in joined.DefaultIfEmpty() where aa == null) select a; But this does not exclude the non null values of aa, and returns all the records just the same as if the 'where aa == null' was not there. Any help is appreciated. Thanks.

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  • LINQ Data Context Not Showing Methods

    - by CccTrash
    For some reason my DataContext is not showing all the normal methods like SubmitChanges() etc in the intellisense. It also won't compile if I type in db.SubmitChanges(); Any idea what I'm doing wrong? Normally I don't have this issue, I have several other projects that work fine... Image of what I'm talking about:

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  • Linq Aggregate function

    - by Nyla Pareska
    I have a List like "test", "bla", "something", "else" But when I use the Aggrate on it and in the mean time call a function it seems to me that after 2 'iterations' the result of the first gets passed in? I am using it like : myList.Aggregate((current, next) => someMethod(current) + ", "+ someMethod(next)); and while I put a breakpoint in the someMethod function where some transformation on the information in the myList occurs, I notice that after the 3rd call I get a result from a former transformation as input paramter.

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  • Linq - get compare with transliterated value of fields

    - by Maxim
    Hi! I have a table (sql server). One of its columns ('Name') Contains Cyrillic values. From parameters i recieve value, that contains in this field but the are transliterated. i mean something like: var q = from r in m_DataContext.Table where CTransliteration.Transliterate(r.Name).Contains(trans_text) select r; How can i transliterate value on-fly?

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  • Using DefaultIfEmpty in Linq - problem substituting a null value for a default value

    - by FiveTools
    I have questions that may or may not have a question_group if all the questions do not have a question_group and if I use default if empty like this: question_group defaultQuestion = new question_group {question_group_id = Guid.Empty}; questions.Select(x => x.question_group).DefaultIfEmpty(defaultQuestion).Distinct(); shouldn't I get an IEnumerable<question_group> containing only the default question_group that I defined? I get null.... what am I missing here?

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  • Three level heirarchal data-linq

    - by user326010
    Hi I have three level heirarchal data. using the statement below i managed to display two level data. I need to extend it to one more level. Current heirachy is Modules--Documents I need to extend it as Packages--Modules--Documents var data = (from m in DataContext.SysModules join d in DataContext.SysDocuments on m.ModuleID equals d.ModuleID into tempDocs from SysDocument in tempDocs.DefaultIfEmpty() group SysDocument by m).ToList(); Regards Tassadaque

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  • Why is doing a top(1) on an indexed column in SQL Server slow?

    - by reinier
    I'm puzzled by the following. I have a DB with around 10 million rows, and (among other indices) on 1 column (campaignid_int) is an index. Now I have 700k rows where the campaignid is indeed 3835 For all these rows, the connectionid is the same. I just want to find out this connectionid. use messaging_db; SELECT TOP (1) connectionid FROM outgoing_messages WITH (NOLOCK) WHERE (campaignid_int = 3835) Now this query takes approx 30 seconds to perform! I (with my small db knowledge) would expect that it would take any of the rows, and return me that connectionid If I test this same query for a campaign which only has 1 entry, it goes really fast. So the index works. How would I tackle this and why does this not work? edit: estimated execution plan: select (0%) - top (0%) - clustered index scan (100%)

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  • ASP.NET LINQ to SQL SubmitChanges() doesn't update the database

    - by Alex
    In my 2nd ASP.NET MVC project I'm facing a very weird problem: when I call the SubmitChanges method of the DataContext class, nothing updates in the database. It's weird because everything works fine with my first project. I'm using a remote database created in Sql Server Management Studio, I tried doing some queries there and in Visual Studio 2010 (where I have the connection to the database), they all work. Where might the problem be hidden?

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  • A better UPDATE method in LINQ to SQL

    - by Refracted Paladin
    The below is a typical, for me, Update method in L2S. I am still fairly new to a lot of this(L2S & business app development) but this just FEELs wrong. Like there MUST be a smarter way of doing this. Unfortunately, I am having trouble visualizing it and am hoping someone can provide an example or point me in the right direction. To take a stab in the dark, would I have a Person Object that has all these fields as Properties? Then what, though? Is that redundant since L2S already mapped my Person Table to a Class? Is this just 'how it goes', that you eventually end up passing 30 parameters(or MORE) to an UPDATE statement at some point? For reference, this is a business app using C#, WinForms, .Net 3.5, and L2S over SQL 2005 Standard. Here is a typical Update Call for me. This is in a file(BLLConnect.cs) with other CRUD methods. Connect is the name of the DB that holds tblPerson When a user clicks save() this is what is eventually called with all of these fields having, potentially, been updated-- public static void UpdatePerson(int personID, string userID, string titleID, string firstName, string middleName, string lastName, string suffixID, string ssn, char gender, DateTime? birthDate, DateTime? deathDate, string driversLicenseNumber, string driversLicenseStateID, string primaryRaceID, string secondaryRaceID, bool hispanicOrigin, bool citizenFlag, bool veteranFlag, short ? residencyCountyID, short? responsibilityCountyID, string emailAddress, string maritalStatusID) { using (var context = ConnectDataContext.Create()) { var personToUpdate = (from person in context.tblPersons where person.PersonID == personID select person).Single(); personToUpdate.TitleID = titleID; personToUpdate.FirstName = firstName; personToUpdate.MiddleName = middleName; personToUpdate.LastName = lastName; personToUpdate.SuffixID = suffixID; personToUpdate.SSN = ssn; personToUpdate.Gender = gender; personToUpdate.BirthDate = birthDate; personToUpdate.DeathDate = deathDate; personToUpdate.DriversLicenseNumber = driversLicenseNumber; personToUpdate.DriversLicenseStateID = driversLicenseStateID; personToUpdate.PrimaryRaceID = primaryRaceID; personToUpdate.SecondaryRaceID = secondaryRaceID; personToUpdate.HispanicOriginFlag = hispanicOrigin; personToUpdate.CitizenFlag = citizenFlag; personToUpdate.VeteranFlag = veteranFlag; personToUpdate.ResidencyCountyID = residencyCountyID; personToUpdate.ResponsibilityCountyID = responsibilityCountyID; personToUpdate.EmailAddress = emailAddress; personToUpdate.MaritalStatusID = maritalStatusID; personToUpdate.UpdateUserID = userID; personToUpdate.UpdateDateTime = DateTime.Now; context.SubmitChanges(); } }

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  • linq get all object in one-dimensional collection

    - by scrat789
    public class Class1 : List<Class2> { } public class Class2 : List<Class3> { } public class Class3 { string str; int i; } public class Program { Class1 c = new Class1(); //insert values.... List<Class3> all = ??; } How can i get a one-dimensional collection in my var "all" ? please note I can not modify Class1, class2 and class3...

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  • LINQ + Find count of non-null values

    - by Ashutosh
    I have a table with the below structure. ID VALUE 1 3.2 2 NULL 4 NULL 5 NULL 7 NULL 10 1.8 11 NULL 12 3.2 15 4.7 17 NULL 22 NULL 24 NULL 25 NULL 27 NULL 28 7 I would like to get the max count of consecutive null values in the table. Any help would be greatly appreciated. THanks Ashutosh

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  • LINQ to SQL - Grouping categories by parentId

    - by creativeincode
    I am trying to construct a navigation menu using a Categories table from my db. I have a similar layout as below in Categories table. public List<Category> CategoryData = new List(new Category[] { new Category{ CategoryId = 1, Name = "Fruit", ParentCategoryId = null}, new Category{ CategoryId = 2, Name = "Vegetables", ParentCategoryId = null}, new Category{ CategoryId = 3, Name = "Apples", ParentCategoryId = 1}, new Category{ CategoryId = 4, Name = "Bananas", ParentCategoryId = 1}, new Category{ CategoryId = 5, Name = "Cucumber", ParentCategoryId = 2}, new Category{ CategoryId = 6, Name = "Onions", ParentCategoryId = 2} ); } The above should return something like Fruit (parent) "===Apples, Bananas (child) Vegetables (parent) "===Cucumber, Onions (child) I need to be able to pass this as some kind of 'grouped' (grouped by parentid) collection to my View. How to do this?

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