Linq Questions

I've got a new instance of an object in a linq dbml, but don't know of the test if the a date field is empty. i have tried:

What's the "best" (taking both speed and readability into account) way to determine if a list is empty? even if the list is of type

I am looking for a more sophisticated way of using linq to sql. i am leaning l2q but i am only seeing simple examples of business objects and

I am trying to inherit from my generated datacontext in linqtosql - something like this public class mycontext : dbdatacontext {

Many applications have grids that display data from a database table one page at a time. many of them also let the user pick the number of records

I want to know how does the sql server know what @p# is in say this linqtosql query select [t0].[memberid],

Okay still fighting with doing some sqlcachedependecy in my asp.net mvc application i got this piece of code from microsoft to cache

I really like entity framework, but there are some key pieces that are a challenge to me. can anyone tell me how to filter an entitydatasource on

My techie bretheren (and sisteren, of course!), i have a linqtosql data model that has the following entities:

I have a list<int> and a list<customobject>. the customobject class has an id property. how can i get a

Is there a pattern using linq to dynamically create a filter? i have the need to create custom filtering on a list, in the past i would

I am prototyping some c# 3 collection filters and came across this. i have a collection of products: public class myproduct {

I have one table "orders" with a foreing key "productid". i want to show the orders in a grid with the product name,

I'm looking for an algorithm to calculate total cost of licenses purchased based on the "fogbugz for your server" pricing scheme

How much database performance overhead is involved with using c# and linq compared to custom optimized queries loaded with mostly low-level c,

Here's my code dim doc = xdocument.load("web.sitemap") i'm trying to load the an xml file so that i can

Yesterday, i asked this question regarding best

So, i am using the linq entity framework. i have 2 entities: content and tag. they are in a many-to-many relationship

I want to inserd new record into my entity table. while binding the records to dropdownlist, we add one new listitem like "- select one

I' trying to use a linq query to find and set the selected value in a drop down list control. dim qry = from i in

I am trying to get the string value "admin" from a linq query, but when i do: string oldmodule = dc.modules

I am generating a dynamic sitemap.xml according to

I have a linq-2-xml query that will not work if a google sitemap that i have created has its urlset element populated with attributes but will

If i have two thousand webusers each sumbmitting a post to sqldb through website at the same time same tables, will linq handle this without any

I created the following extension: public static class stacktraceextensions { public static string callers(this stacktrace

I need to replace the contents of a node in an xelement hierarchy when the element name and all the attribute names and values match an input

I'm trying to select the "name" field from the author node in an atom feed using linq. i can get all the fields i need like so:

I seem to be missing something about linq. to me, it looks like it's taking some of the elements of sql that i like the least and moving them

I have a class that looks like this public class vegetablespricenode { public string country{get;set;} public

If i have 2 int arrays a and b and they contain data like this.. a[0] = 1 a[1] = 3 a[2] = 7 b[0] = 6 b[1] = 3 b[2] =

Why am i getting a textbox that returns undefined list of variables? when i run this code: var query = (from tisa in

It is the first time i'm using the query mode of ef core. because my large query with parameters threw also the exception "sequence contains

In my database a have rows like

I'm getting crazy about that. maybe you could help. assume having the following .net classes: teacher:

There is a data set as ienumerable<t> griddata which is bound to a data grid. in one scenario data loaded with t

I am looking for a way to return only distinct elements in an array but that has to be based on a certain property, other properties of the array

I am trying to fetch elements having a common id from 2 sets of arrays but that id must be unique to each array, the array can contain

I have an array of tuple arrays like this: (type, func<int, bool>)[][] formats; i also

I'm trying to console.writeline my answer but i am missing something and after 2 hours of searching, i just can't figure it out. i want my

I have an application and a database created by entity framework core, i have an entity called listusers with this property:

I am working on a blazor project and using dapper to pull data from a sql db. i am pulling 3 tables at the moment. an entity table, a specialty

(type, int)[] format1 = new[] {(typeof(foo),1)}; (type, int)[] format2 = new[] { (typeof(bar), 1),(typeof(baz),1) };

I am trying to solve a problem as well as learn and improve my code skills here. i am using entity framework and am tasked with writing to

I need to reduce data from a class as given below (pk ... primary key, fk ... foreign key):

So i want to display an output that is group by two fields: subsidiarycode and assetcreateddate. my problem is it

I have an isession.queryover code block. in where clause, there is a problem as shown below var receipts= isession.queryover(()

I am having trouble getting the count by its type.

I can't figure it out and tested some answers from similare questions. now i need a linq pro. :) the following query with linq returns each

I am creating a web application to manage a flight school and i have the following database structure (unrelevant tables have been blurred and

How could merge nested child entity in parent? i have these three entities: public

Portalselectslist.firstordefault(x => x.portalid == item.portalid).accesstypeportalid = item.accesstypeportalid;

Look at this iqueryable: var query = from e in db.entitya select new myviewmodel {

I'm trying to make a simple script in vb that will transform a string "these are my characters" into this "these are my characters" it

I have a method in which i filter a table and return those rows that match the filer. here's the method: public

I have this class: public class student1 { public string name { set; get; } public string number { set;

I have this class: public class course { public string name { set; get; } public int code { set; get; } public

So i have two repositories: repository a which gets info from database a and repository b which

So, i have a function that returns data for use in a gridview. it takes ages to complete (about 25 seconds). i think i've written it very badly

I heard lots of reviews on the book linq in action, but it does not cover linq to entities. please provide your feedback on the books you

I'm trying to group my data using linq. this is the model i use: public class employee { public string firstname {get;set;}

I am new to linq & i can't figure out this query. i have a datatable with has a field "recordtype" i want to get certain row

I have this query below that looks for a transfer with a user id in either the senderid or receiverid column. //

I'm trying to convert an object to a dto public class topology { public int a { get; set; } public int b { get; set; } }

I have the following sql query and i want to convert it to linq expression select `a`.* from `action` as `a` where `a`.`id` in (

I am trying to link two fields of a given table to the same field in another table. i have done this before so i can't work out what is wrong this

I'm trying to use system.xml.linq to create xhtml documents. thus, the vast majority of the nodes in my trees ought to use this

If i have an xelement that has child elements, and if i remove a child element from the parent, removing all references between the two, will the

To store and query on associated ids, which method works best in terms of query speed and performance? especially in a large number of records in

I'm using c# wpf to connect to a database in sql server i have a combobox that have two column to display with one selectedvaluepath

I am trying to print "title of the book , authornames " (some books have more than one author) below linq code is printing only first author. how

I'm having some issues with a query i wrote in python (have to use it for tensorflow), which works just fine but is way too slow, since the input

I am currently working with real-estate data, and each listing entity has a listingdate and a closedate. what i am currently trying to do is to

I have a lambda expression that is passed to a first() or firstordefault() call. i would like to dynamically

I have an object that i need to get some fields from just the first one matched. the key thing is "prices" will either be sorted in

I found this question, which is similar to a problem that i would like to solve:

Ref to:creating a validationattribute

This query was working fine before we upgraded: var appusers = await _masterdbcontext .users

My model looks like below public class country { public int id {get; set;} public string name {get; set;} } public class user

I am using convert.todecimal in linq, sometime amount value coming as dot (.) as user might want to write .50 or something,

I am dealing with probably simple yet difficult problem for me. i am taking photos of parked cars and save them by car's plate and timestamp it.

I am trying to select "highest" licence user has per year. i started with: var lic = _context.licences

I'm new to javascript and i just wanted to know if there is a linq equivalent in vue. my goal is to do something like this :

I have the following linq query (using ef core 6 and ms sql server): var resultset = dbcontext.systems .include(system

Hey all i have a issue with trying to use lambda with my variable simply because its not a key, value type of setup. meaning i don't

I get the sequence number 0 ~ 2 with ienumerable and when i print the result. the ienumerable and ienumerable.tolist()

I have two related tables like below : users : public partial class users {

In my application i have textbox in a formview bound to a linqdatasource like so:

Sorry if the title isn't clear, i couldn't think of a good way to summarise the question. suppose i have a database table called

I have a database table which contains one to many data collection. from that table i need to make a dictionary which represents the data. the key

I have a list of items and a list of itemscontainer which is a class that holds items. all the items are unique every item

I have a query here and its working in sql, but i am using linq and i don't know how to convert it. can anyone help me? this is my

I am trying to sort date field in string format with invalid/null values. however, i am not getting the expected result. var

I have an entity framework database that i'm querying, so i'm using linq-to-entities. here's my query: // 'find' is just a wrapper

I'm looking for help finding an extension method for takelast that someone has written that can work for older versions of .net framework like 4.6

I have status tables in my database, and "localised" tables that contain language-specific versions of those statuses. the point of the main

I have 2 models. model foo [system.data.linq.mapping.table(name = ...)] public class foo {

I have two tables cars and booking. i want the following sql query's equivalent in linq and i'm struggling with

I have a table for payslips which can contain multiple payslips with the same employee. each payslip has a hours_worked column. i want to be able

I have an array of data and i need to group them by 2 attributes and then calculate the sum of a third attribute per each group. i want to do this

I have 3 tables: contract, matter and claims. each table has a 1:n relationship with the following table. i want to select claim