linq

problem in using Distinct with Linq

Hi Everyone, Hi have an issue with Linq. I have an array of double values with duplicate entries. I want to extract only distinct values from it. I have the following code which doesn't work correctly. double[] dIds = GetIds(); //dIds has more than 10,000 items var itemIdCollection = from id in dIds.Distinct() selec...

Make CSV from list of string in LINQ

Hi I would like to take a list collection and generate a single csv line. So take this; List<string> MakeStrings() { List<string> results = new List<string>(); results.add("Bob"); results.add("Nancy"); results.add("Joe"); results.add("Jack"); } string ContactStringsTogether(List<string> parts) { StringBu...

Enabling Service Broker in SQL Server 2008

Hello, I am integrating SqlCacheDependency to use in my LinqToSQL datacontext. I am using an extension class for Linq querys found here - http://code.msdn.microsoft.com/linqtosqlcache I have wired up the code and when I open the page I get this exception - "The SQL Server Service Broker for the current database is not enabled, and a...

Populate a tree from Hierarchical data using 1 LINQ statement

Hi. I have set up this programming exercise. using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace ConsoleApplication2 { class DataObject { public int ID { get; set; } public int ParentID { get; set; } public string Data { get; set; } public DataObject(int id, ...

Select most recent records using LINQ to Entities

I have a simple Linq to Enities table to query and get the most recent records using Date field So I tried this code: IQueryable<Alert> alerts = GetAlerts(); IQueryable<Alert> latestAlerts = from a in alerts group a by a.UpdateDateTime into g select g.OrderBy(a => a.Identifier).First(); Error: NotSupportedException: ...

how to order a group result with Linq?

How can I order the results from "group ... by... into..." statement in linq? For instance: var queryResult = from records in container.tableWhatever where records.Time >= DateTime.Today group records by tableWhatever.tableHeader.UserId into userRecords select new { UserID = userRec...

parsing expression trees with booleans

I am trying to parse an expression tree for a linq provider and running into a little snag with booleans. I can parse this no problems. var p = products.Where(x=>x.IsAvailable == true).ToList(); however when its written like this? var p = products.Where(x=>x.IsAvailable).ToList(); i only get a MemberAccess to look at and i can't s...

Combine 3 sequences

I have three string arrays. I want to combine them using zip in linq. How to do? arr1.Zip(arr2, (a1, a2) => a1 + a2); How to add arr3? ...

Quickly or concisely determine the longest string per column in a row-based data collection

Judging from the result of my last inquiry, I need to calculate and preset the widths of a set of columns in a table that is being made into an Excel file. Unfortunately, the string data is stored in a row-based format, but the widths must be calculated in a column-based format. The data for the spreadsheets are generated from the follow...

ASP.NET MVC <OutputCache> SqlDependency (CommandNotification?) with LINQ queries

Hello, I use LINQ queries in my ASP.NET MVC application and want to use OutputCache in some of my Actions. I hear this should be possible with CommandNotifications. But those seem to only go for self-created SQLCommands, or am I wrong? Can I manually tell SQL server to send SQLDependency notifications if certain tables change? And if...

How do I combine these similar linq queries into one?

This is probably a basic LINQ question. I have need to select one object and if it is null select another. I'm using linq to objects in the following way, that I know can be done quicker, better, cleaner... public Attrib DetermineAttribution(Data data) { var one = from c in data.actions where ...

Most efficient algorithm for merging sorted IEnumerable<T>

Hello, I have several huge sorted enumerable sequences that I want to merge. Theses lists are manipulated as IEnumerable but are already sorted. Since input lists are sorted, it should be possible to merge them in one trip, without re-sorting anything. I would like to keep the defered execution behavior. I tried to write a naive algor...

Linq join with COUNT

I have 2 tables, Forums and Posts. I want to retrieve all Forums fields with a new extra field: count all post that belong to this forum. I have this for now: var v =(from forum in Forums join post in Posts on forum.ForumID equals post.Forum.ForumID select new { forum, //Need to retrieve all fields/columns from fo...

How to avoid geometric slowdown with large Linq transactions?

I've written some really nice, funky libraries for use in LinqToSql. (Some day when I have time to think about it I might make it open source... :) ) Anyway, I'm not sure if this is related to my libraries or not, but I've discovered that when I have a large number of changed objects in one transaction, and then call DataContext.GetCha...

C# Joins/Where with Linq and Lambda

Hello, I'm having trouble with a query written in Linq and Lambda. So far, I'm getting a lot of errors here's my code: int id = 1; var query = database.Posts.Join(database.Post_Metas, post => database.Posts.Where(x => x.ID == id), meta => database.Post_Metas.Where(x => x....

Need help with a Linq XML conditional grouping query

I have the following xml fragment: <BANNER ID="Banner 2" ROW_WIDTH="200"> <BANNER_TEXTS ID="BANNER_TEXTS"> <BANNER_TEXT UNDERLINE="false" SPAN_COL="1" WIDTHT="78px"></BANNER_TEXT> <BANNER_TEXT UNDERLINE="true" SPAN_COL="3" WIDTHT="234px">Years In Practice</BANNER_TEXT> <BANNER_TEXT UNDERLINE="true" SPAN_COL="3" WIDTHT...

linq to sql using foreign keys returning iqueryable(of myEntity]

I'm trying to use Linq to SQL to return an IQueryable(of Project) when using foreign key relationships. Using the below schema, I want to be able to pass in a UserId and get all the projects created for the company the user is associated with. DB tables: Projects Projid ProjCreator FK (UserId from UserInfo table) Companyid FK (Co...

How to Zip one IEnumerable with itself

I am implementing some math algorithms based on lists of points, like Distance, Area, Centroid, etc. Just like in this post: http://stackoverflow.com/questions/2227828/find-the-distance-required-to-navigate-a-list-of-points-using-linq That post describes how to calculate the total distance of a sequence of points (taken in order) by es...

Properly handling possible System.NullReferenceException in lambda expressions

Here's the query in question return _projectDetail.ExpenditureDetails .Where(detail => detail.ProgramFund == _programFund && detail.Expenditure.User == _creditCardHolder) .Sum(detail => detail.ExpenditureAmounts.FirstOrDefault( amount => amount.isCurrent && !amount.requiresAudit) .CommittedMonthlyRecord.Proj...

How can i replicate in mi bd server from .NET using LINQ?

I have a data model on LINQ in my project wich i generated from a DB on SQL Server the problem is that all the changes that i make only have effect in the Local DB on my project but not in the web SQL server, how can i replicate the changes automatically? ...