Search Results

Search found 4739 results on 190 pages for 'linq compiledquery'.

Page 76/190 | < Previous Page | 72 73 74 75 76 77 78 79 80 81 82 83  | Next Page >

• Query data using LINQ to SQL and Entity Framework with foreign key? (Help me please)

  - by The Wind

  Hello! There is a problem I need help with your query on the data using LINQ to SQL and Entity Framework (I'm using Visual Studio 2010). My picure here: http://img.tamtay.vn/files/photo2/2010/5/28/10/962/4bff3a3b_1093f58f_untitled-1.gif I have three tables: tbl NewsDetails tblNewsCategories tblNewsInCategories (See screen 1 in my picture) Now, I want to retrieve records in the tblNewsDetails table, with condition: CategoryId=1, as the following results: (See screen 2 in my picture) But NewsID and CategoryId in tblNewsInCategories table is two foreign key, I do not see them and I do not know how to use them in your code. My code has errors: (See screen 3 in my picture) Please help me. Thanks! (I am a new member, should not have the right to insert images)

  Read the article

• What's elegant way to rewrite following LINQ statement using extension methods?

  - by Jakub Šturc

  I have following LINQ statement and I want to rewrite it using extension methods. from x in e from y in e from z in e select new { x, z } One possible solution is: e.Join(e, x => 42, y => 42, (x, y) => new { x, y }) Join(e, _ => 42, z => 42, (_, z) => new { _.x, z }); However this is everything but elegant. Do you any idea how to improve beauty of second expression?

  Read the article

• How can I subsample data from a time series with LINQ to SQL?

  - by Chris Farmer

  I have a database table full of time points and experimental values at those time points. I need to retrieve the values for an experiment and create a thumbnail image showing an XY plot of its data. Because the actual data set for each experiment is potentially 100,000 data points and my image is only 100 pixels wide, I want to sample the data before creating the image. My current query (which retrieves all the data without sampling) is something simple like this: var points = from p in db.DataPoints where p.ExperimentId == myExperimentId orderby p.Time select new { X = p.Time, Y = p.Value } So, how can I best take every nth point from my result set in a LINQ to SQL query?

  Read the article

• How do I improve the efficiency of the queries executed by this generic Linq-to-SQL data access clas

  - by Lee D

  Hi all, I have a class which provides generic access to LINQ to SQL entities, for example: class LinqProvider<T> //where T is a L2S entity class { DataContext context; public virtual IEnumerable<T> GetAll() { return context.GetTable<T>(); } public virtual T Single(Func<T, bool> condition) { return context.GetTable<T>().SingleOrDefault(condition); } } From the front end, both of these methods appear to work as you would expect. However, when I run a trace in SQL profiler, the Single method is executing what amounts to a SELECT * FROM [Table], and then returning the single entity that meets the given condition. Obviously this is inefficient, and is being caused by GetTable() returning all rows. My question is, how do I get the query executed by the Single() method to take the form SELECT * FROM [Table] WHERE [condition], rather than selecting all rows then filtering out all but one? Is it possible in this context? Any help appreciated, Lee

  Read the article

• C#: How to remove items from the collection of a IDictionary<E, ICollection<T>> with LINQ?

  - by Rosarch

  Here is what I am trying to do: private readonly IDictionary<float, ICollection<IGameObjectController>> layers; foreach (ICollection<IGameObjectController> layerSet in layers.Values) { foreach (IGameObjectController controller in layerSet) { if (controller.Model.DefinedInVariant) { layerSet.Remove(controller); } } } Of course, this doesn't work, because it will cause a concurrent modification exception. (Is there an equivalent of Java's safe removal operation on some iterators?) How can I do this correctly, or with LINQ?

  Read the article

• How do I transfer this logic into a LINQ statement?

  - by Geoffrey

  I can't get this bit of logic converted into a Linq statement and it is driving me nuts. I have a list of items that have a category and a createdondate field. I want to group by the category and only return items that have the max date for their category. So for example, the list contains items with categories 1 and 2. The first day (1/1) I post two items to both categories 1 and 2. The second day (1/2) I post three items to category 1. The list should return the second day postings to category 1 and the first day postings to category 2. Right now I have it grouping by the category then running through a foreach loop to compare each item in the group with the max date of the group, if the date is less than the max date it removes the item. There's got to be a way to take the loop out, but I haven't figured it out!

  Read the article

• LINQ and paging with a DataTable - can't get Skip working?

  - by Kit Menke

  Ok so this might be a dumb question, but I can't seem to figure it out. I thought I'd try out LINQ against a DataTable. I got my query working and now I'm trying to implement some simple paging. DataTable dataTable = null; dataTable = GetAllDataTables(); var query = from r in dataTable.AsEnumerable() orderby r.Field<string>(Constants.fileName) select r; query.Skip(WPP_PAGE_SIZE * pageIndex).Take(WPP_PAGE_SIZE); My problem is that I get an error at query.Skip(...). Error 1 'System.Data.OrderedEnumerableRowCollection' does not contain a definition for 'Skip' and no extension method 'Skip' accepting a first argument of type 'System.Data.OrderedEnumerableRowCollection' could be found (are you missing a using directive or an assembly reference?) References I have: Microsoft.SharePoint System System.Core System.Data System.Data.DataSetExtensions System.Web System.Xml What am I missing?

  Read the article

• Clone LINQ To SQL object Extension Method throws object dispose exception....

  - by gtas

  Hello all, I have this extension method for cloning my LINQ To SQL objects: public static T CloneObjectGraph<T>(this T obj) where T : class { var serializer = new DataContractSerializer(typeof(T), null, int.MaxValue, false, true, null); using (var ms = new System.IO.MemoryStream()) { serializer.WriteObject(ms, obj); ms.Position = 0; return (T)serializer.ReadObject(ms); } } But while i carry objects with not all references loaded, while qyuerying with DataLoadOptions, sometimes it throws the object disposed exception, but thing is I don't ask for references that is not loaded (null). e.g. I have Customer with many references and i just need to carry on memory the Address reference EntityRef< and i don't Load anything else. But while i clone the object this exception forces me to load all the EntitySet< references with the Customer object, which might be too much and slow down the application speed. Any suggestions?

  Read the article

• Possible to use Tables of same type in Linq to SQL?

  - by Schneider

  Lets say I've got an object model, where I have many collections of the same type. For example something like class StockMarketData { List<SummaryData> WeeklySummary; List<SummaryData> MonthlySummary; } class SummaryData { DateTime DateTime {get; set;} double Value {get; set;} } Those lists will map onto database tables. If you actually use L2S to generate a model from the database you will get something like: class StockMarketData { List<WeeklySummaryData> WeeklySummary; List<MonthlySummaryData> MonthlySummary; } Even though WeeklySummaryData and MonthlySummaryData have the same shape. Is it possible for Linq to SQL to create tables from a database of summary data, but get each table to contain the same type (such as shown in the top example).

  Read the article

• Can anyone tell me if this is possible to do in Linq?

  - by user275561

  So I have been working and trying for a couple of hours. I am creating a BubbleBreaker type of game. I Can do it using for loop or while but I am trying to also get practice in using Linq. Here is what I am trying to do in pesudo code. Each Bubble has a Column and Row Property. If The bubble subtracts one from its Column property and finds the same Color bubble, it should Select it then Subtract -1 and see if two bubbles away there is also a same color bubble. If there is then subtract -2 and so on. So What I am trying to do is var test= _theBubbles.TakeWhile((i, s) => i.BubbleColor== bubble.BubbleColor)//Then somehow tell it to do bubble.Column-s and then Subtract s from bubble.Column So the Idea is to keep looking down the column till the bubble isnt the same

  Read the article

• How to pull a RANDOM and UNIQUE record from SQL via LINQ.

  - by Jeremy H

  Okay, I found lots of posts on SO about how to pull a RANDOM item from the database when using LINQ. There seems to be a couple of differnet ways to handle this. What I need to do though is pull a RANDOM item from the database that the user has not seen before. The data I am pulling from the database is very small. Is there any way I can just hit the database once for 1000 records and then randomly scroll through those? Should I put a cookie on the users system recording the IDs of which items they have seen, pull a random record, check to see if it is seen and if so, pull from the database again? That seems like performance issues just waiting to happen. I don't expect anyone to code it for me, I am just looking for concepts and pointing in the right direction of how I should go about this. Need more details? Just let me know!

  Read the article

• How do I add multiple joins (Fetches) to a joined table using nhibernate and LINQ ?

  - by ooo

  i have these tables /entities VacationRequestDate table which has a VacationRequestId field that links with VacationRequest table VacationRequest has PersonId and RequestStatusId fields that links with Person and RequestStatus respectively. i have this query so far: IEnumerable<VacationRequestDate> dates = Session.Query<VacationRequestDate>().Fetch(r => r.VacationRequest).ThenFetch(p=>p.RequestStatus).ToList(); this works fine and joins with VacationRequest and then VacationRequest joins with RequestStatus but i can't figure out how to add an additional EAGER join to the VacationRequest table. If i add a Fetch at the end, it refers to the VacationRequestDate table If i add a ThenFetch at the end, it refers to the RequestStatus table I can't find any api that will refer to the VacationRequest table as the reference point. how would you add multiple joins to a joined table using nhibernate LINQ ?

  Read the article

• How can I transform a DataTable in a group-by date DataTable with LINQ?

  - by alex

  I have a untyped DataTable that looks like this (srcTbl): date col_1 col_2 ... col_n 1.3.2010 00:00 12.5 0 ... 100 1.3.2010 01:00 0 0 ... 100 1.3.2010 22:00 0 0 ... 100 1.3.2010 23:00 12.5 0 ... 100 ... 31.3.2010 00:00 2 0 ... 100 31.3.2010 01:00 2 0 ... 200 I need to sum up the rows grouped by dates to get a DataTable like that (dstTbl): date, col_1 col_2 ... col_n 1.3.2010 15 0 ... 400 ... 31.3.2010 4 0 ... 300 Is this possible by using LINQ and if then how?

  Read the article

• How to do Linq aggregates when there might be an empty set?

  - by Shaul

  I have a Linq collection of Things, where Thing has an Amount (decimal) property. I'm trying to do an aggregate on this for a certain subset of Things: var total = myThings.Sum(t => t.Amount); and that works nicely. But then I added a condition that left me with no Things in the result: var total = myThings.Where(t => t.OtherProperty == 123).Sum(t => t.Amount); And instead of getting total = 0 or null, I get an error: System.InvalidOperationException: The null value cannot be assigned to a member with type System.Decimal which is a non-nullable value type. That is really nasty, because I didn't expect that behavior. I would have expected total to be zero, maybe null - but certainly not to throw an exception! What am I doing wrong? What's the workaround/fix?

  Read the article

• C# / Entity Framework / Linq question regarding calling a method when a class is accessed...

  - by Daniel

  So this is probably really basic, but I'm fairly new to all this. I am using Entity Framework with POCO entities. I want to call a method when a class property is set. I am trying to build an advertisement platform. I have a Customer class, a Venue class and an Advertisement class. I have my indexes set up in such a way that I can call customer.venue. However, I want to be able to call Customer.Venue.CurrentAdvertisement and have it execute a method (if CurrentAdvertisement is null) and return the current advertisement. I know I can explicitly set it every time, but I want to be able to override my classes so that whenever the CurrentAdvertisement property is accessed via LINQ it runs that method to return an ad. In order to do this I need to pass the Venue class a variable (venue name).

  Read the article

• What are the best blogs for staying up to date on C#, ASP.NET, LINQ, SQL, C++, Ruby, Java, Python?

  - by Arj

  Apologies if this repeats another - but I couldn't fine one like it. My day to day programming spans a fair number of technologies: C#, ASP.NET, LINQ / SQL, C++, Ruby, Java, Python in approximately that order. It's a struggle to keep up to date on any of best practices, new ideas, innovation and improvements, let alone all. Therefore, what would your top 1 blog be in each of these technologies and which technology do you find easiest to stay up to date with? I'd have a bias towards blogs with broad and high level rather than narrow and detailed content / solutions / examples.

  Read the article

• ASP.NET MVC / Linq-to-SQL classes: Can I get it to infer readable display names?

  - by Gary McGill

  If I have a table Orders with fields CustomerID, OrderID and OrderDate, then the "Linq-to-SQL classes" generated class will be called Orders, with members called CustomerID, OrderID and OrderDate. So far so good. However, if I then do Html.LabelFor(m => m.OrderDate) then the generated text will be "OrderDate" instead of "Order Date". I tried using Order_Date as the field name, but that didn't work. Is there any way to get it to infer a better display name? [I know that I can use data annotations to specify the display name explicitly, but I really don't want to do that for all my classes/members - I just want it to work by convention.]

  Read the article

• Another Permutation Word Conundrum... With Linq?

  - by CraigF

  I have seen many examples of getting all permutations of a given set of letters. Recursion seems to work well to get all possible combinations of a set of letters (though it doesn't seem to take into account if 2 of the letters are the same). What I would like to figure out is, could you use linq (or not) to get all possible combinations of letters down to 3 letter combinations. For example, given the letters: P I G G Y I want an array of all possible cominations of these letters so I can check against a word list (scrabble?) and eventually get a list of all possible words that you can make using those letters (from 3 letters up to the total, in this case 5 letters).

  Read the article

• What is the max LINQ Expression Trees can do?

  - by yeeen

  What is the maximun that LINQ expression Tree can do? Can it define a class? How about a method, with all the declared name, modifiers, parametertype and return type? Must the program always define the tree himself? Is it possible to generate the tree from a given C# file? Where can I get resources to learn about writing basic to advanced Expression Tree and Expression Tree Visitor? (articles and videos will be great) Thanks for those who are able to help...

  Read the article

• Can I use Linq to project a new typed datarow?

  - by itchi

  I currently have a csv file that I'm parsing with an example from here: http://alexreg.wordpress.com/2009/05/03/strongly-typed-csv-reader-in-c/ I then want to loop the records and insert them using a typed dataset xsd to an Oracle database. It's not that difficult, something like: foreach (var csvItem in csvfile) { DataSet.MYTABLEDataTable DT = new DataSet.MYTABLEDataTable(); DataSet.MYTABLERow row = DT.NewMYTABLERow(); row.FIELD1 = csvItem.FIELD1; row.FIELD2 = csvItem.FIELD2; } I was wondering how I would do something with LINQ projection: var test = from csvItem in csvfile select new MYTABLERow { FIELD1 = csvItem.FIELD1, FIELD2 = csvItem.FIELD2 } But I don't think I can create datarows like this without the use of a rowbuilder, or maybe a better constructor for the datarow?

  Read the article

• why LINQ 2 SQL sometime add a field like select 1 as test, others valid fields....

  - by Fredou

  I have to concat 2 linq2sql query and I have an issue since the 2 query doesn't return the same number of columns, what is weird is after a .ToList() on the queries, they can concat without problem. The reason is, for some linq2sql reason, I have 2 more column named test and test2 which come from 2 left outer join that linq2sql automatically create, something like "select 1 as test, tablefields" Is there any good reason for that? how to remove this extra "1 as test" field? here a few of examples of what it look like: google result for linq 2 sql "select 1 as test"

  Read the article

• Tag filtering Query using T-SQL and Linq-to-SQL?

  - by EdenMachine

  I'm trying to figure out how to allow a user to enter in a string of tags (keywords separated by spaces) in a textbox to filter a grid of results. Here are the tables: PACKETS *PacketID Name PACKETTAGS *PacketTagID PacketID TagID Tags *TagID Name Here is the basic query without the WHERE parameters: SELECT Packets.Name, Tags.Name AS Tag, PacketTags.PacketTagID FROM Packets INNER JOIN PacketTags ON Packets.PacketID = PacketTags.PacketID INNER JOIN Tags ON PacketTags.TagID = Tags.TagID I need to filter out all the Packets that don't have tags that match any of the words BUT ALSO ONLY include the Packets that have the tags entered in the string of text (spaces separate the tags when entered into the textbox) I'm starting with the basics by figuring this out in t-SQL first but ultimately I need to be able to do this in Linq-to-SQL

  Read the article

• How to OrderBy on a generic IEnumerable (IEnumerable<T>) using LINQ in C#?

  - by Jeffrey

  In my generic repository I have below method: public virtual IEnumerable<T> GetAll<T>() where T : class { using (var ctx = new DataContext()) { ctx.ObjectTrackingEnabled = false; var table = ctx.GetTable<T>().ToList().AsReadOnly(); return table; } } T is a Linq to Sql class and I want to be able to OrderBy on a particular property. Say if T has property name "SortOrder" then do OrderBy on this property. But I am not sure how I can achieve this. So I need some helps. Thank you!

  Read the article

• Using Where method in Linq 2 Entities with OR clause.

  - by Dani

  I want to use Where method in Linq 2 entities that will be equal to this userRepository.Users.Where(u=>u.RoleID == 1 || u=>u.RoldID == 2).Select(o => new SelectListItem { Text = o.Role.RoleName, Value = o.RoleID.ToString() }).ToList(); The problem of course is in Where(u=u.RoleID == 1 || u=u.RoldID == 2) The problem is that I don't know how to use WHERE method with OR inside the WHERE clause. any ideas (the code above will not compile of-course b/c of the lambda expression. userRepository.Users returns an list of Users entities. I guess that and can be done using concatenation of .Where().Where() but I need an OR.

  Read the article

• How to update a table in database using LINQ in F#?

  - by sudaly

  I have seen plenty of examples on how to query the database but nothing on how to update records. Below is the simple code that I wrote to retrieve a table, but can someone explain me how can I modify a field, say lastActiveDate, and update the table on the database Thank you, suday open System open Microsoft.FSharp.Linq let connString = "Server=localhost;Database=myDb;Trusted_Connection=True;" let db = new MyDb(connString) db.Log <- System.Console.Out let res = Query.query <@ seq { for users in db.userAccounts do yield users } @> |> List.ofSeq printfn "Totla users: %d" res.Length

  Read the article

< Previous Page | 72 73 74 75 76 77 78 79 80 81 82 83  | Next Page >