linq

Crystal Report and LINQ

I am using Crystal Report for creating a report. I have two tables, Driver_Specifications and WatchRow. Primary key of WatchRow is foreign key of Driver_Specifications. I set some field in my report file to show the data of Driver_Specifications and I want to show a specific field of WatchRow instead of the foreign key of Driver_Specifi...

Determine the relative complement of two IEnumerable<T> sets in .NET

Is there an easy way to get the relative complement of two sets? Perhaps using LINQ? I have to find the relative compliment of a set A relative to B. Both A and B are of type HashSet<T> but I think the algorithm could be made more general (IEnumerable<T> or even ISet<T>)? I could use a solution in either VB.NET or C#. ...

Inspection of Insert Statement When Using LINQ's SubmitChanges

Hi. I want to see what my insert statement would look like as if I was wiring up an text-based ADO.NET command. How do I do this? I have been following the below link: http://damieng.com/blog/2008/07/30/linq-to-sql-log-to-debug-window-file-memory-or-multiple-writers And have added the DebugTextWriter class to my project. So, now, i...

Expression.OrElse, dynamically creating a condition.

Hi, I am attempting to create a dynamic where clause using the standard expression API. var query = ( from p in Parties orderby p.PartyId orderby p.FullName select p ).AsQueryable(); Expression<Func<Party, bool>> @fn = (p) => SqlMethods.Like(p.FullName, "%smith%") || SqlMet...

Request all titles by actor using LINQ to Netflix OData

I'm experimenting with LINQPad to use LINQ to query the Netflix OData. I'm trying to search for all films with a particular actor in. For example: from t in Titles from p in t.Cast where p.Name == "Morgan Freeman" select t.Name this results in: NotSupportedException: Can only project the last entity type in the query being transl...

Stored Functions with Linq to Entities

Hi, How can I make a MS-SQL stored function availabe in LINQ expressions if using the Entity framework? The SQL function was created with CREATE FUNCTION MyFunction(@name) ...). I was hoping to access it similarly to this: var data = from c in entities.Users where MyFunction(c.name) = 3; Unfortunately I have only .NET 3.5 available....

LINQ - more than or equal to

Part of the code: ...where se.DateFrom >= pDateFrom && se.DateTo <= pDateTo select se... Does not work. There is no any error but the To and From days do not get returned. How do I query "more than or equal to" and "less than or equal to"? Thanks :) ...

How to refactor this duplicated LINQ code?

I am trying to figure out how to refactor this LINQ code nicely. This code and other similar code repeats within the same file as well as in other files. Sometime the data being manipulated is identical and sometimes the data changes and the logic remains the same. Here is an example of duplicated logic operating on different fields of ...

Simplest LINQ in C# troubleshooting.

I'm trying to learn a bit of LINQ but I'm having compile issues right off the bat. Is there any specific reason why this won't work? using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace HelloLINQ { class HelloLINQ { public static void Main() { Example...

Change C# sorting behaviour

Lets say i have the strings abc_ and abc2_. Now, normally when sorting i C# abc2_ would come after abc_, leaving the result: abc_ abc2_ I am using this to sort, if it matters: var element = from c in elements orderby c.elementName ascending select c; How can i change this? I want abc_ to come last. Reversing is not ...

SubSonic IQueryable To String Array

Hey All, I have decided to use SubSonic (v3.0) for the first time and thoroughly enjoy it so far however I seem to have stumbled and I am hoping there is a nice neat solution. I have a users, roles and joining table. SubSonic (ActiveRecord) generated an entity User for my users table. A property of User is UserRoles and is of the type...

Searching with Linq

I have a collection of objects, each with an int Frame property. Given an int, I want to find the object in the collection that has the closest Frame. Here is what I'm doing so far: public static void Search(int frameNumber) { var differences = (from rec in _records select new { FrameDiff = Math.Abs(rec.Frame...

LINQ: GroupBy with maximum count in each group

Hi, I have a list of duplicate numbers: Enumerable.Range(1,3).Select(o => Enumerable.Repeat(o, 3)).SelectMany(o => o) // {1,1,1,2,2,2,3,3,3} I group them and get quantity of occurance: Enumerable.Range(1,3).Select(o => Enumerable.Repeat(o, 3)).SelectMany(o => o) .GroupBy(o => o).Select(o => new { Qty = o.Count(), Num = o.Key }) ...

LINQ transform Dictionary<key,value> to Dictionary<value,key>

I'm having a low-brainwave day... Does anyone know of a quick & elegant way to transform a Dictionary so that the key becomes the value and vice-versa? Example: var originalDictionary = new Dictionary<int, string>() { {1, "One"}, {2, "Two"}, {3, "Three"} ...

EF/LINQ: Where() against a property of a subtype

I have a set of POCOs, all of which implement the following simple interface: interface IIdObject { int Id { get; set; } } A subset of these POCOs implement this additional interface: interface IDeletableObject : IIdObject { bool IsDeleted { get; set; } } I have a repository hierarchy that looks something like this:...

Refactoring - Speed increase

How can I make this function more efficient. It's currently running at 6 - 45 seconds. I've ran dotTrace profiler on this specific method, and it's total time is anywhere between 6,000ms to 45,000ms. The majority of the time is spent on the "MoveNext" and "GetEnumerator" calls. and example of the times are 71.55% CreateTableFromReport...

Linq-to-sql join/where?

I've the following table structures Users id Types id isBool UsersTypes userid types I want to select all the UserTypes based on id and isBool. I tried this query var q = from usertype in usertypes from type in types where type.isBool == false where userstypes.user == id select usertype; But thi...

LINQ's pathetic handling of composite keys

I have a table that has a composite key that consists of two int fields and one varchar(50) field. I made the composite key my primary key, which I don't usually do. Yes, yes, yes, I'm more than familiar with the logical key vs. surrogate key debate, but I must have done some heavy drugs (not really) the day that I made the table since I...

Selecting a value from multiple dictionaries inside an enumeration

If I have an enumeration of dictionaries IEnumerable<IDictionary<string, float>> enumeration can I perform a Linq query on it so that I can select by a value from each dictionary in the enumeration using the same key? I can do this in a loop: float f; foreach (var dictionary in enumeration) { if (dictionary.TryGetValue("some key...

Most efficient way to bind a Listbox with SelectionMode=Multiple

Hi, I have an ASP.NET webform that has a listbox (lbxRegions) with multi-select option enabled. In my db, I have a table with an xml field that holds a list of regions. I need to populate the listbox with all available regions and then "check off" the list items that match the regions in the db table. The list options also need to be ord...