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  • Advanced LINQ Update Statement

    - by user1902490
    I have a data base with Price_old like: Date --- Hour --- Price _____________________________ Jan 1 --- 1 --- $3.0 Jan 1 --- 2 --- $3.1 Jan 1 --- 3 --- $3.3 Jan 1 --- 4 --- $3.15 Jan 2 --- 1 --- $2.95 Jan 2 --- 2 --- $3.2 Jan 2 --- 3 --- $3.05 What I then have is a spreadsheet, with the same structure, that I will be reading into a datatable, I'll call the new datatable Price_New, note that price new may not have all the same date/hours as Price_Old So, I end up with 2 datatables, Price_Old, and Price_New, and what I need to do is update Price_old with the new prices in Price_New, and then commit those new prices to the Database. I am kinda new to LINQ (about 30 mins of experience) and would really appreciate if someone could give me a pointer or two on whether or not this is doing in LINQ and what the best method would be. Thanks

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  • Performance on joins in linq

    - by swapna
    HI , I am going to rewrite a store procedure in LINQ. What this sp is doing is joining 12 tables and get the data and insert it into another table. it has 7 left outer joins and 4 inner joins.And returns one row of data. Now question. 1)What is the best way to achieve this joins in linq. 2) do you think this affect performance (its only retrieving one row of data at a given point of time) Please advice. Thanks SNA.

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  • querying databases on same server with linq

    - by geoff swartz
    In normal sql I could do joins on tables in different databases as long as they were on the same server (or linked servers). In linq I can't figure out how to do that. Is this possible? For example, if I have a database called db1 and another called db2. db1 has a table called people and db2 has a table called address I could do something like... select a.addressline1, p.firstname from db1.dbo.people p inner join db2.dbo.address a on p.peopleid = a.peopleid Is this possible with linq? Thanks.

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  • linq "let" translation

    - by luke
    I understand that when the C# compiler sees a linq query comprehension, it basically does a straight translation to the corresponding Linq Extension methods and lambdas. i.e. from x in list select x.property gets translated to: list.Select(x => x.property) my question is what do let clauses get translated to. for example how would this get translated by the compiler. from x in list let v = SomeComplexExpressionDependingOnx select v (p.s. i know this could be reduced to just select SomeComplexExpressionDependingOnx but i want to know how this is done in general) Thanks!

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  • Storing object as a column in LINQ

    - by Alex
    Hello, i have some class which constructs itself from string, like this: CurrencyVector v = new CurrencyVector("10 WMR / 20 WMZ"); it's actually a class which holds multiple currency values, but it does not matter much. I need to change type of column in my LINQ table (in vs 2010 designer) from String to that class, CurrencyVector. If i do it - i get runtime error when LINQ runtime tries to cast String as CurrencyVector (when populating the table from database). Adding IConvertible did not help. I wrapped these columns in properties, but it's ugly and slow solution. Searching internet gave no results.

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  • LINQ count query returns a 1 instead of a 0

    - by user335810
    I have the following view:- CREATE VIEW tbl_adjudicator_result_view AS SELECT a.adjudicator_id, sar.section_adjudicator_role_id, s.section_id, sdr.section_dance_role_id, d.dance_id, c.contact_id, ro.round_id, r.result_id, c.title, c.first_name, c.last_name, d.name, r.value, ro.type FROM tbl_adjudicator a INNER JOIN tbl_section_adjudicator_role sar on sar.section_adjudicator_role2adjudicator = a.adjudicator_id INNER JOIN tbl_section s on sar.section_adjudicator_role2section = s.section_id INNER JOIN tbl_section_dance_role sdr on sdr.section_dance_role2section = s.section_id INNER JOIN tbl_dance d on sdr.section_dance_role2dance = d.dance_id INNER JOIN tbl_contact c on a.adjudicator2contact = c.contact_id INNER JOIN tbl_round ro on ro.round2section = s.section_id LEFT OUTER JOIN tbl_result r on r.result2adjudicator = a.adjudicator_id AND r.result2dance = d.dance_id When I run the following query directly against the db I get 0 in the count column where there is no result select adjudicator_id, first_name, COUNT(result_id) from tbl_adjudicator_result_view arv where arv.round_id = 16 group by adjudicator_id, first_name However when I use LINQ query I always get 1 in the Count Column var query = from arv in db.AdjudicatorResultViews where arv.round_id == id group arv by new { arv.adjudicator_id, arv.first_name} into grp select new AdjudicatorResultViewGroupedByDance { AdjudicatorId = grp.Key.adjudicator_id, FirstName = grp.Key.first_name, Count = grp.Select(p => p.result_id).Distinct().Count() }; What do I need to change in the View / Linq query.

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  • Help needed with Linq To Sql Query

    - by fearofawhackplanet
    I have the concept of valid/ordered transitions. So for example, it's not possible to move to status In progress from status Complete. Current and Next in table StatusTransition are FK (StatusType.Id). The Linq generator has created the following relations: Child Property Name: StatusTransitions1 Parent Property Name: StatusType1 Participating Properties: StatusType.Id -> StatusTransition.Next Child Property Name: StatusTransitions Parent Property Name: StatusType Participating Properties: StatusType.Id -> StatusTransition.Current I'm normally ok with Linq but I'm having difficulty getting the list of valid Next StatusTypes from the Current status. public List<StatusType> GetValidStatusTransitions(int statusId) { // trying to write something like the following // (obviously not correct) return _statusRepository .Where(s => s.Id == statusId) .Next.StatusTypes; }

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  • linq 'not in' query not resolving to what I expect

    - by Fiona
    I've written the following query in Linq: var res = dc.TransactionLoggings .Where( x => !dc.TrsMessages(y => y.DocId != x.DocId) ).Select(x => x.CCHMessage).ToList(); This resolves to the following: SELECT [t0].[CCHMessage] FROM [dbo].[TransactionLogging] AS [t0] WHERE NOT (EXISTS( SELECT NULL AS [EMPTY] FROM [dbo].[TrsMessages] AS [t1] WHERE [t1].[DocId] <> [t0].[DocId] )) Which always returns null Basiaclly what I'm trying to write is the following Select cchmessage from transactionlogging where docid not in (select docid from trsmessages) Any suggestions on what's wrong with my LINQ statment? Many thanks, Fiona

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  • Linq to NHibernate - How to include parent object and only certain child objects

    - by vakman
    Given a simplified model like the following: public class Enquiry { public virtual DateTime Created { get; set; } public virtual Sender Sender { get; set; } } public class Sender { public virtual IList<Enquiry> Enquiries { get; set; } } How can you construct a Linq to Nhibernate query such that it gives you back a list of senders and their enquiries where the enquiries meet some criteria. I have tried something like this: return session.Linq<Enquiry>() .Where(enquiry => enquiry.Created < DateTime.Now) .Select(enquiry => enquiry.Sender) In this case I get an InvalidCastException saying you can't cast type Sender to type Enquiry. Any pointers on how I can do this without using HQL?

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  • Linq query joining with a subquery

    - by Alan Fisher
    I am trying to reproduce a SQL query using a LINQ to Entities query. The following SQL works fine, I just don't see how to do it in LINQ. I have tried for a few hours today but I'm just missing something. SELECT h.ReqID, rs.RoutingSection FROM ReqHeader h JOIN ReqRoutings rr ON rr.ReqRoutingID = (SELECT TOP 1 r1.ReqRoutingID FROM ReqRoutings r1 WHERE r1.ReqID = h.ReqID ORDER BY r1.ReqRoutingID desc) JOIN ReqRoutingSections rs ON rs.RoutingSectionID = rr.RoutingSectionID Edit*** Here is my table scema- Requisitions: ReqID PK string ReqDate datetime etc... ReqRoutings: ID PK int ReqID FK RoutingSection FK int RoutingDate ReqRoutingSections: Id PK int RoutingSection string The idea is that each Requisition can be routed many times, for my query I need the last RoutingSection to be returned along with the Requisition info. Sample data: Requisitions: - 1 record ReqID 123456 ReqDate '12/1/2012' ReqRoutings: -- 3 records id 1 ReqID 123456 RoutingSection 3 RoutingDate '12/2/2012' id 2 ReqID 123456 RoutingSection 2 RoutingDate '12/3/2012' id 3 ReqID 123456 RoutingSection 4 RoutingDate '12/4/2012' ReqRoutingSections: -- 3 records id 2 Supervision id 3 Safety id 4 Qaulity Control The results of the query would be ReqID = '123456' RoutingSection = 'QualityControl' -- Last RoutingSection requisition was routed to

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  • Linq to NHibernate - How to return a parent object with only certain child objects included

    - by vakman
    Given a simplified model like the following: public class Enquiry { public virtual DateTime Created { get; set; } public virtual Sender Sender { get; set; } } public class Sender { public virtual IList<Enquiry> Enquiries { get; set; } } How can you construct a Linq to Nhibernate query such that it gives you back a list of senders and their enquiries where the enquiries meet some criteria. I have tried something like this: return session.Linq<Enquiry>() .Where(enquiry => enquiry.Created < DateTime.Now) .Select(enquiry => enquiry.Sender) In this case I get an InvalidCastException saying you can't cast type Sender to type Enquiry. Any pointers on how I can do this without using HQL?

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  • Jointure in linq with a regular expression

    - by Graveen
    I'm actually using a join in linqtosql (via dblinq). I'm trying to include a regular expression in the join part of the linq query. from i in collectiona join j in collectionb on Regex.IsMatch(i.name, j.jokered_name) equals true (...) I agree i can push the RegExp check in the where part of the linq query, but i was wondering if it is possible in the join part ? The above code wants an "i equals j" code structure. One thing i think to perform is overriding Equals() which 'll contains the RegEx.IsMatch() stuff and put a simple i equals j in the join part. Any suggestions about my problem ?

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  • Filtering subsets using Linq

    - by Nathan Matthews
    Hi All, Imagine a have a very long enunumeration, too big to reasonably convert to a list. Imagine also that I want to remove duplicates from the list. Lastly imagine that I know that only a small subset of the initial enumeration could possibly contain duplicates. The last point makes the problem practical. Basically I want to filter out the list based on some predicate and only call Distinct() on that subset, but also recombine with the enumeration where the predicate returned false. Can anyone think of a good idiomatic Linq way of doing this? I suppose the question boils down to the following: With Linq how can you perform selective processing on a predicated enumeration and recombine the result stream with the rejected cases from the predicate?

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  • LINQ - group specific types of classes

    - by Nelson
    This question is similar to http://stackoverflow.com/questions/2835192/linq-group-one-type-of-item but handled in a more generic way. I have a List that has various derived classes. I may have something like this: List<BaseClass> list = new List<BaseClass>() { new Class1(1), new Class2(1), new Class1(2), new Class3(1), new Class2(2), new Class4(1), new Class3(2) }; I am trying to use LINQ to semi-sort the list so that the natural order is maintained EXCEPT for certain classes which have base.GroupThisType == true. All classes with GroupThisType should be grouped together at the place that the first class of the same type occurs. Here is what the output should be like: List<BaseClass> list = new List<BaseClass>() { new Class1(1), new Class1(2), new Class2(1), new Class3(1), new Class3(2) new Class2(2), new Class4(1), };

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  • MVC | Linq Update Query | Help!

    - by 109221793
    Hi guys, I'm making modifications to a C# MVC application that I've inherited. I have a database, and for simplicity I'll just focus on the two tables I'm working with for this linq query. Item ItemID Int PK ItemName RepairSelection (Yes or No) RepairID Int FK Repair RepairID Int PK RepairCategory SubmissionDate DateSentForRepair Ok, so ItemID is pretty much the identifier, and the View to display the Repair details goes like this (snippet): <%= Html.LabelFor(x => x.ItemID)%> <%= Html.DisplayFor(x => x.ItemID)%><br /> <%= Html.LabelFor(x => x.Repair.RepairCategory)%> <%= Html.DisplayFor(x => x.Repair.RepairCategory, "FormTextShort")%><br /> <%= Html.LabelFor(x => x.Repair.SubmissionDate)%> <%= Html.DisplayFor(x => x.Repair.SubmissionDate)%><br /> <%= Html.LabelFor(x => x.Repair.DateSentForRepair)%> <%= Html.DisplayFor(x => x.Repair.DateSentForRepair)%><br /> <%= Html.ActionLink("Edit Repair Details", "Edit", new { ItemID= Model.ItemID})%> Here is the GET Edit action: public ActionResult Edit(Int64? itemId) { ModelContainer ctn = new ModelContainer(); var item = from i in ctn.Items where i.ItemID == itemId select i; return View(item.First()); } This is also fine, the GET Edit view displays the right details. Where I'm stuck is the linq query to update the Repair table. I have tried it so many ways today that my head is just fried (new to Linq as you may have guessed). My latest try is here (which I know is way off so go easy ;-) ): [HttpPost] public ActionResult Edit(Int64 itemId, Repair repair, Item item, FormCollection formValues) { if (formValues["cancelButton"] != null) { return RedirectToAction("View", new { ItemID = itemId }); } ModelContainer ctn = new ModelContainer(); Repair existingData = ctn.Repair.First(a => a.RepairId == item.RepairID && item.ItemID == itemId); existingData.SentForConversion = DateTime.Parse(formValues["SentForConversion"]); ctn.SaveChanges(); return RedirectToAction("View", new { ItemID = itemId }); } For the above attempt I get a Sequence Contains No Elements error. Any help or pointers would be appreciated. Thanks guys.

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  • LINQ in SQLite for Windows store app does not have 'ThenBy' to order by multiple columns

    - by user1131657
    I have a Windows 8 store application and I'm using the latest version on SQLite for my database. So I want to return some records from the database and I want to order them by more that one column. However SQLite doesn't seem to have the ThenBy statement? So my LINQ statement is below: from i in connection.Table<MyTable>() where i.Type == type orderby i.Usage_Counter // ThenBy i.ID select i); So how do I sort by multiple columns in SQLite without doing another LINQ statement?

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  • Duplicate a database record with linq

    - by holz
    Is there a way to duplicate a db record with linq to sql in c#? Id [int] IDENTITY(1,1) NOT NULL PRIMARY KEY, [Foo] [nvarchar](255) NOT NULL, [Bar] [numeric](28,12) NOT NULL, ... Given the table above, I would like to duplicate a record (but give it a different id), in a way that new fields added to the DB and the Linq dbml file at a later date will still get duplicated with out having to change that code that duplicates the record. ie I don't want to write newRecord.Foo = currentRecord.Foo; for all of the fields on the table.

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  • Linq To SQL: Retain list order when using .Contains

    - by rockinthesixstring
    I'm using Lucene.net to build a MyListOfIds As List(Of Integer) which I then pass on to my Linq service. I then search the database as follows Return _EventRepository.Read().Where(Function(e) MyListOfIds.Contains(e.ID)).ToList Now I know that Lucene is already ordering MyListOfIds based on the weight it gave each term. What sucks is that Linq is losing that order in it's SQL search. My Question: How can I retain that sort order when building my Lambda expression? I tried using LINQPad to see how the query is being built, but because I had to declare a variable LINQPad didn't show me the resultant SQL :-( Here's what I tried in LINQPad Dim i As New List(Of Integer) i.Add(1) i.Add(100) i.Add(15) i.Add(3) i.Add(123) Dim r = (From e In Events Where i.Contains(e.ID) Select e) note: my example is in VB.NET, but I don't mind if responses are in C#

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  • Sort collection within collection using Linq

    - by user327066
    Hi, I have a one-to-many Linq query and I would like to sort on a property within the "many" collection. For example in the pseudo-code below, I am returned a List from the Linq query but I would like to sort / order the Products property based on the SequenceNumber property of the Product class. How can I do this? Any information is appreciated. Thanks. class Order { int OrderId; List<Product> Products; } class Product { string name; int SequenceNumber; }

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  • Multiple fields from LINQ to Text Box

    - by Chuki2
    how can I pass value from selected field (LINQ) to textbox in winforms? If single fields, I just do like this var result = from row in dtValueBranch.AsEnumerable() where row.Field<int>("branchID") == idBranch select row.Field<string>("branchName"); StringBuilder sb = new StringBuilder(); foreach (string s in result) { sb.Append(s + Environment.NewLine); } tbBranch.Text = sb.ToString(); So this is the code LINQ to many fields var result = from row in dtValueBranch.AsEnumerable() where row.Field<int>("branchID") == idBranch select new { BranchName = row["branchName"].ToString(), branchTel = row["branchTel1"].ToString(), // And many more fields }; How can I to implement each fields to each textbox?

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