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  • linq and contains

    - by kusanagi
    i have func public PageOfList<ConsaltQuestion> Filter(int? type, int pageId, EntityCollection<ConsaltCost> ConsaltRoles) { // return _dataContext.ConsaltQuestion.Where((o => o.Type == type || type == null) && (o=>o.Paid == paid)); return (from i in _dataContext.ConsaltQuestion where ((i.Type == type || type == null) && (i.Paid == true) && (ConsaltRoles.Contains(ConsaltCostDetails(i.Type.Value)))) select i).ToList().ToPageOfList(pageId, 20); } it return error LINQ to Entities does not recognize the method 'Boolean Contains(mrhome.Models.ConsaltCost)' method, and this method cannot be translated into a store expression. how can i fix it?

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  • Reconciling a new BindingList into a master BindingList using LINQ

    - by Neo
    I have a seemingly simple problem whereby I wish to reconcile two lists so that an 'old' master list is updated by a 'new' list containing updated elements. Elements are denoted by a key property. These are my requirements: All elements in either list that have the same key results in an assignment of that element from the 'new' list over the original element in the 'old' list only if any properties have changed. Any elements in the 'new' list that have keys not in the 'old' list will be added to the 'old' list. Any elements in the 'old' list that have keys not in the 'new' list will be removed from the 'old' list. I found an equivalent problem here - http://stackoverflow.com/questions/161432/ - but it hasn't really been answered properly. So, I came up with an algorithm to iterate through the old and new lists and perform the reconciliation as per the above. Before anyone asks why I'm not just replacing the old list object with the new list object in its entirety, it's for presentation purposes - this is a BindingList bound to a grid on a GUI and I need to prevent refresh artifacts such as blinking, scrollbars moving, etc. So the list object must remain the same, only its updated elements changed. Another thing to note is that the objects in the 'new' list, even if the key is the same and all the properties are the same, are completely different instances to the equivalent objects in the 'old' list, so copying references is not an option. Below is what I've come up with so far - it's a generic extension method for a BindingList. I've put comments in to demonstrate what I'm trying to do. public static class BindingListExtension { public static void Reconcile<T>(this BindingList<T> left, BindingList<T> right, string key) { PropertyInfo piKey = typeof(T).GetProperty(key); // Go through each item in the new list in order to find all updated and new elements foreach (T newObj in right) { // First, find an object in the new list that shares its key with an object in the old list T oldObj = left.First(call => piKey.GetValue(call, null).Equals(piKey.GetValue(newObj, null))); if (oldObj != null) { // An object in each list was found with the same key, so now check to see if any properties have changed and // if any have, then assign the object from the new list over the top of the equivalent element in the old list foreach (PropertyInfo pi in typeof(T).GetProperties()) { if (!pi.GetValue(oldObj, null).Equals(pi.GetValue(newObj, null))) { left[left.IndexOf(oldObj)] = newObj; break; } } } else { // The object in the new list is brand new (has a new key), so add it to the old list left.Add(newObj); } } // Now, go through each item in the old list to find all elements with keys no longer in the new list foreach (T oldObj in left) { // Look for an element in the new list with a key matching an element in the old list if (right.First(call => piKey.GetValue(call, null).Equals(piKey.GetValue(oldObj, null))) == null) { // A matching element cannot be found in the new list, so remove the item from the old list left.Remove(oldObj); } } } } It can be called like this: _oldBindingList.Reconcile(newBindingList, "MyKey") However, I'm looking for perhaps a method of doing the same using LINQ type methods such as GroupJoin<, Join<, Select<, SelectMany<, Intersect<, etc. So far, the problem I've had is that each of these LINQ type methods result in brand new intermediary lists (as a return value) and really, I only want to modify the existing list for all the above reasons. If anyone can help with this, would be most appreciated. If not, no worries, the above method (as it were) will suffice for now. Thanks, Jason

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  • beginner Linq syntax and EF4 question

    - by user564577
    Question With the following linq code snip I get a list of clients with address filtered by the specifications but the form of the entities returned is not what i had expected. The data is 1 client with 2 addresses and 1 client with 1 address. The query returns 3 rows of clients each with 1 address Client 1 = Address1 Client 1 = Address2 Client 2 = Address3 var query = from t1 in context.Clients.Where(specification.SatisfiedBy()).Include("ClientAddresses") join t2 in context.ClientAddresses.Where(spec.SatisfiedBy()) on t1.ClientKey equals t2.ClientKey select t1; My expectation was a little more like a list with only two clients in it, one client with a collection of two addresses and one client with a collection of one address. Client 1 = Address1 / Address2 Client 2 = Address3 What am I missing??? Thanks!

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  • Translating Where() to sql

    - by MBoros
    Hi. I saw DamienG's article (http://damieng.com/blog/2009/06/24/client-side-properties-and-any-remote-linq-provider) in how to map client properties to sql. i ran throgh this article, and i saw great potential in it. Definitely mapping client properties to SQL is an awesome idea. But i wanted to use this for something a bit more complicated then just concatenating strings. Atm we are trying to introduce multilinguality to our Business objects, and i hoped we could leave all the existing linq2sql queries intact, and just change the code of the multilingual properties, so they would actually return the given property in the CurrentUICulture. The first idea was to change these fields to XMLs, and then try the Object.Property.Elements().Where(...), but it got stuck on the Elements(), as it couldnt translate it to sql. I read somewhere that XML fields are actually regarded as strings, and only on the app server they become XElements, so this way the filtering would be on the app server anyways, not the DB. Fair point, it wont work like this. Lets try something else... SO the second idea was to create a PolyGlots table (name taken from http://weblogic.sys-con.com/node/102698?page=0,1), a PolyGlotTranslations table and a Culture table, where the PolyGlots would be referenced from each internationalized property. This way i wanted to say for example: private static readonly CompiledExpression<Announcement, string> nameExpression = DefaultTranslationOf<Announcement> .Property(e => e.Name) .Is(e=> e.NamePolyGlot.PolyGlotTranslations .Where(t=> t.Culture.Code == Thread.CurrentThread.CurrentUICulture.Name) .Single().Value ); now unfortunately here i get an error that the Where() function cannot be translated to sql, what is a bit disappointing, as i was sure it will go through. I guess it is failing, cause the IEntitySet is basically an IEnumerable, not IQueryable, am i right? Is there another way to use the compiledExpressions class to achieve this goal? Any help appreciated.

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  • LinqToSql Select to a class then do more queries

    - by fyjham
    I have a LINQ query running with multiple joins and I want to pass it around as an IQueryable<T> and apply additional filters in other methods. The problem is that I can't work out how to pass around a var data type and keep it strongly typed, and if I try to put it in my own class (EG: .Select((a,b) => new MyClass(a,b))) I get errors when I try to add later Where clauses because my class has no translations into SQL. Is there any way I can do one of the following: Make my class map to SQL? Make the var data-type implement an interface (So I can pass it round as though it's that)? Something I haven't though of that'll solve my issue? Example: public void Main() { using (DBDataContext context = new DBDataContext()) { var result = context.TableAs.Join( context.TableBs, a => a.BID, b => b.ID, (a,b) => new {A = a, B = b} ); result = addNeedValue(result, 4); } } private ???? addNeedValue(???? result, int value) { return result.Where(r => r.A.Value == value); } PS: I know in my example I can flatten out the function easily, but in the real thing it'd be an absolute mess if I tried.

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  • Linq2Sql: query - subquery optimisation

    - by Budda
    I have the following query: IList<InfrStadium> stadiums = (from sector in DbContext.sectors where sector.Type=typeValue select new InfrStadium(sector.TeamId) ).ToList(); and InfrStadium class constructor: private InfrStadium(int teamId) { IList<Sector> teamSectors = (from sector in DbContext.sectors where sector.TeamId==teamId select sector) .ToList<>(); ... work with data } Current implementation perform 1+n queries, where n - number of records fetched the 1st time. I want to optimize that. And another one I would love to do using 'group' operator in way like this: IList<InfrStadium> stadiums = (from sector in DbContext.sectors group sector by sector.TeamId into team_sectors select new InfrStadium(team_sectors.Key, team_sectors) ).ToList(); with appropriate constructor: private InfrStadium(int iTeamId, IEnumerable<InfrStadiumSector> eSectors) { IList<Sector> teamSectors = eSectors.ToList(); ... work with data } But attempt to launch query causes the following error: Expression of type 'System.Int32' cannot be used for constructor parameter of type 'System.Collections.Generic.IEnumerable`1[InfrStadiumSector]' Question 1: Could you please explain, what is wrong here, I don't understand why 'team_sectors' is applied as 'System.Int32'? I've tried to change query a little (replace IEnumerable with IQueryeable): IList<InfrStadium> stadiums = (from sector in DbContext.sectors group sector by sector.TeamId into team_sectors select new InfrStadium(team_sectors.Key, team_sectors.AsQueryable()) ).ToList(); with appropriate constructor: private InfrStadium(int iTeamId, IQueryeable<InfrStadiumSector> eSectors) { IList<Sector> teamSectors = eSectors.ToList(); ... work with data } In this case I've received another but similar error: Expression of type 'System.Int32' cannot be used for parameter of type 'System.Collections.Generic.IEnumerable1[InfrStadiumSector]' of method 'System.Linq.IQueryable1[InfrStadiumSector] AsQueryableInfrStadiumSector' Question 2: Actually, the same question: can't understand at all what is going on here... P.S. I have another to optimize query idea (describe here: Linq2Sql: query optimisation) but I would love to find a solution with 1 request to DB).

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  • Grouping by property value and writing group members

    - by Will S
    I need to group the following list by the department value but am having trouble with the LINQ syntax. Here's my list of objects: var people = new List<Person> { new Person { name = "John", department = new List<fields> {new fields { name = "department", value = "IT"}}}, new Person { name = "Sally", department = new List<fields> {new fields { name = "department", value = "IT"}}}, new Person { name = "Bob", department = new List<fields> {new fields { name = "department", value = "Finance"}}}, new Person { name = "Wanda", department = new List<fields> {new fields { name = "department", value = "Finance"}}}, }; I've toyed around with grouping. This is as far as I've got: var query = from p in people from field in p.department where field.name == "department" group p by field.value into departments select new { Department = departments.Key, Name = departments }; So can iterate over the groups, but not sure how to list the Person names - foreach (var department in query) { Console.WriteLine("Department: {0}", department.Department); foreach (var foo in department.Department) { // ?? } } Any ideas on what to do better or how to list the names of the relevant departments?

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  • Seperating entities from their actions or behaviours

    - by Jamie Dixon
    Hi everyone, I'm having a go at creating a very simple text based game and am wondering what the standard design patterns are when it comes to entities (characters, sentient scenery) and the actions those entities can perform. As an example, I have entity that is a 'person' with various properties such as age, gender, height, etc. This 'person' can also perform some actions such as speaking, walking, jumping, flying, etc etc. How would you seperate out the entity from the actions it can perform and what are some common design patterns that solve this kind of problem?

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  • Split List into Sublists with LINQ

    - by Felipe Lima
    Hi all, I believe this is another easy one for you LINQ masters out there. Is there any way I can separe a List into several separate lists of SomeObject, using the item index as the delimiter of each split? Let me exemplify: I have a List<SomeObject> and I need a List<List<SomeObject>> or List<SomeObject>[], so that each of these resulting lists will contain a group of 3 items of the original list (sequentially). eg.: Original List: [a, g, e, w, p, s, q, f, x, y, i, m, c] Resulting lists: [a, g, e], [w, p, s], [q, f, x], [y, i, m], [c] I'd also need the resulting lists size to be a parameter of this function. Is it possible?? Thanks!

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  • Why LINQ to Entities won't let me initialize just some properties of an Entity?

    - by emzero
    So I've started to add Entity Framework 4 into a legacy web application (ASP.NET WebForms). As a start I have auto-generated some entities from the database. Also I want to apply Repository Pattern. There is an entity called Visitor and its repository VisitorRepository In VisitorRepository I have the following method: public IEnumerable<Visitor> GetActiveVisitors() { var visitors = from v in _context.Visitors where v.IsActive select new Visitor { VisitorID = v.VisitorID, EmailAddress = v.EmailAddress, RegisterDate = v.RegisterDate, Company = v.Company, Position = v.Position, FirstName = v.FirstName, LastName = v.LastName }; return visitors.ToList(); } That List is then bound to a repeater and when trying to do <%# Eval('EmailAddress') #%> it throws the following exception. The entity or complex type 'Model.Visitor' cannot be constructed in a LINQ to Entities query. A) Why is this happening? How I can workaround this? Do I need to select an anonymous type and then use that to initialize my entities??? B) Why every example I've seen makes use of 'select new' (anonymous object) instead of initializing a known type? Anonymous types are useless unless you are retrieving the data and showing it in the same layer. As far as I know anonymous types cannot be returned from methods? So what's the real point of them??? Thank you all

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  • Linq to sql Invalid column name

    - by Ivo
    I am using VS 2010 and Linq-to-sql I have deleted a couple of columns from my table, whatever I try I keep getting and "invalide column name" error with the old/deleted column when I try to insert a record. What tried: remove table,save, and drag it back on create new dblm with an other name created new project and create new dbml there Also the name of the deleted column does not exist in the generated code of the dbml anymore, but still I get an exception saying that column does not exists. Anyone got a suggestion how to solve this problem?

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  • Linq: Converting flat structure to hierarchical

    - by Stefan Steinegger
    What is the easiest and somewhat efficient way to convert a flat structure: object[][] rawData = new object[][] { { "A1", "B1", "C1" }, { "A1", "B1", "C2" }, { "A2", "B2", "C3" }, { "A2", "B2", "C4" } // .. more }; into a hierarchical structure: class X { public X () { Cs = new List<string>(); } public string A { get; set; } public string B { get; set; } public List<string> Cs { get; private set; } } the result should look like this // pseudo code which describes structure: result = { new X() { A = "A1", B = "B1", Cs = { "C1", "C2" } }, new X() { A = "A2", B = "B2", Cs = { "C3", "C4" } } } Preferably using Linq extension methods. Target class X could be changed (eg. a public setter for the List), only if not possible / useful as it is now.

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  • Use LINQ to query nested OData collection

    - by Kyle Russell
    I'm playing around with the new Netflix OData feed (http://odata.netflix.com/Catalog/) and having some issues. I'm trying to learn LINQ at the same time but having difficulty doing what I thought was going to be quite simple. I'd like to return a list of Titles that match a given Genre. The Titles object contains a collection of Genres. I'm not sure how to write this query. My attempt below does not appear to work using LINQPad. from t in Titles where t.Genres.Name.Contains("ABC") select t

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  • Request all titles by actor using LINQ to Netflix OData

    - by Mark Heath
    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 translated I also tried: from p in People from t in p.TitlesActedIn where p.Name == "Morgan Freeman" select t.Name which results in the following error: NotSupportedException: The method 'Select' is not supported I've tried a few other approaches, such as using Id's in the where clause, and selecting different things, but have got nowhere.

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  • creating Linq to sqlite dbml from DbLinq source code

    - by Veer
    Hi All, I tried to create linq-to-sqlite dbml using DbLinq but in vain. Each time I get different type of errors. May be I'm somewhere wrong. Can anyone tell me the step by step procedure to create the dbml file from the Dblinq source code. Edit: Steps I Followed: I downloaded the source file from this link. Edited the "run_sqliteMetal.bat" file in \\DbLinq-0.19\src\DbMetal folder as 'DbMetal.exe -database:myDb.db3 -namespace:myNS -code:myCode.cs' -dbml:myDbml.dbml Tried to run the DbMetal project file to produce the executable but there was a runtime error since Options object in Parameters.cs was null. Hence downloaded the readymade exe file from this location Copied it into the \DbLinq-0.19\src\DbMetal folder Executed the "run_sqliteMetal.bat" file I got a blank screen and Windows Error Msg "DbLinq has stopped Working" Any help? Thanks in advance, Veer

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  • How to create an ObservableCollection using LINQ in Silverlight

    - by sonofpirate
    In a non-Silverlight world, it is easy to use LINQ to create an ObservableCollection. This is because the ObservableCollection class has constructors that accept any IEnumerable<T or List<T. However, the Silverlight version does not! This means that code such as: var list = (from item in e.Result select new ViewModel(item)).ToList(); Items = new System.Collections.ObjectModel.ObservableCollection<ViewModel>(list); will not work in Silverlight. Is there another option to make this work besides resorting to a for-each statement?

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  • Linq filtering an IQueryable<T> (System.Data.Linq.DataQuery) object by a List<T> (System.Collection.

    - by Klaptrap
    My IQueryable line is: // find all timesheets for this period - from db so System.Data.Linq.DataQuery var timesheets = _timesheetRepository.FindByPeriod(dte1, dte2); My List line is: // get my team from AD - from active directory so System.Collection.Generic.List var adUsers = _adUserRepository.GetMyTeam(User.Identity.Name); I wish to only show timesheets for those users in the timesheet collection that are present in the user collection. If I use a standard c# expression such as: var teamsheets = from t in timesheets join user in adUsers on t.User1.username equals user.fullname select t; I get the error "An IQueryable that returns a self-referencing Constant expression is not supported" Any recommendations?

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  • List<T>.SelectMany(), Linq and lambda help

    - by jim
    Hi there I have a class. public class MedicalRequest { private int id private IList<MedicalDays> Days private string MedicalUser ... } and another public class MedicalDays { private int id; private DateTime? day private MedicalRequest request ... } I'm using nhibernate to return a list of all the MedicalDays within a time span. I'd like to do something like this to the resulting list //nhibernate query IList<MedicalDays> days = daysDao.FindAll(searchCritCollection); //select a list of days from resulting list IEnumerable<MedicalDays> queriedList = days.SelectMany(i => i.MedicalRequest.MedicalUser == employee); Linq tells me that the type cannot be inferred by the usage. I'd like to know what I'm doing wrong, and if there is a preferred way of doing something like this. Thanks for your time.

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  • SQL Server CE, Visual Studio 2008/2010 RC, and Linq-to-Sql

    - by blu
    I added an .sdf to my project, added a table, added a Linq-to-Sql dmbl, and tried to add the table to the dbml. The result was an error: "The selected object(s) are an unsupported data provider" This happens in both VS 2008 Professional SP1 and 2010 RC Ultimate. I found someone talking about using SQL Metal to generate the file, but I didn't enjoy that 2 years ago, and after a little playing around I recall why. Does anyone know if this is going to be supported in the release version? Should I abandon SQL Server CE and just use SQLite (with DbLinq)? Thanks for any insight.

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  • Crystal report using Linq-to-sql

    - by DATT OZA
    Hello, I am bit confusing in generating crystal report from linq-to-sql object in my WpfApplication. crystalreport1 rpt = new crystalreport1(); datacontextclass1 db = new datacontextclass1(); var q = (from records in db.emp select records).toList(); rpt.setDataSource(q); crystalviewer.reportsource(rpt); I have done above steps... but its prompts error NotSupportedException Was Unhandled Dataset not support system.nullable< please help... thanx in advance..

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  • how to group by over anonymous type with vb.net linq to object

    - by smoothdeveloper
    I'm trying to write a linq to object query in vb.net, here is the c# version of what I'm trying to achieve (I'm running this in linqpad): void Main() { var items = GetArray( new {a="a",b="a",c=1} , new {a="a",b="a",c=2} , new {a="a",b="b",c=1} ); ( from i in items group i by new {i.a, i.b} into g let p = new{ k = g, v = g.Sum((i)=>i.c)} where p.v > 1 select p ).Dump(); } // because vb.net doesn't support anonymous type array initializer, it will ease the translation T[] GetArray<T>(params T[] values){ return values; } I'm having hard time with either the group by syntax which is not the same (vb require 'identifier = expression' at some places, as well as with the summing functor with 'expression required' ) Thanks so much for your help!

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  • What's the convention for extending Linq with set based helper operations

    - by Luke Rohde
    Hi All I might be vaguing out here but I'm looking for a nice place to put set based helper operations in linq so I can do things like; db.Selections.ClearTemporary() which does something like db.DeleteAllOnSubmit(db.Selections.Where(s => s.Temporary)) Since I can figure out how to extend Table<Selection> the best I can do is create a static method in partial class of Selection (similar to Ruby) but I have to pass in the datacontext like; Selection.ClearTemporary(MyDataContext) This kind of sucks because I have two conventions for doing set based operations and I have to pass the data context to the static class. I've seen other people recommending piling helper methods into a partial of the datacontext like; myDataContext.ClearTemporarySelections(); But I feel this makes the dc a dumping ground for in-cohesive operations. Surely I'm missing something. I hope so. What's the convention? TIA

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  • VB.NET GroupBy LINQ statement

    - by Jason
    I am having a bear of a time getting this to work. I have a List(Of MyItem) called Items that have a OrderId property on them. From those items, I want to create a list of Orders. Some items will have the same OrderId so I want to try to group by OrderId. I then want to sort by date. Here's what I have so far: Public ReadOnly Property AllOrders() As List(Of Order) Get Return Items.Select(Function(i As MyItem) New Order(i.OrderID)) _ .GroupBy(Function(o As Order) New Order(o.OrderID)) _ .OrderBy(Function(o As Order) o.DateOrdered).ToList End Get End Property This, of course, doesn't compile, and I get the error: Value of type 'System.Collections.Generic.List(Of System.Linq.IGrouping(Of Order, Order))' cannot be converted to 'System.Collections.Generic.List(Of Order))' I've bolded the part where I think the problem is, but I have no idea how to fix it. Also, it used to work fine (except there were duplicate values) before I added the .GroupBy statement. Anyone have any ideas? Thanks

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  • JSINQ (Linq for JavaScript library) sub-queries (how-to)

    - by Tom Tresansky
    I'm using this library: jsinq. I want to create a new object using subqueries. For example, in .NET LINQ, I could do something like this: from a in Attendances where a.SomeProperty = SomeValue select new { .Property1 = a.Property1, .Property2 = a.Property2, .Property3 = (from p in People where p.SomeProperty = a.Property3 select p) } such that I get a list of ALL people where Property3 value matches the attendance's Property3 value in EACH object returned in the list. I didn't see any sample of this in the docs or on the playground. Made a couple tries of it and didn't have any luck. Anybody know if this is possible and how to?

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  • T-SQL IsNumeric() and Linq-to-SQL

    - by cdonner
    I need to find the highest value from the database that satisfies a certain formatting convention. Specifically, I would like to fund the highest value that looks like EU999999 ('9' being any digit) select max(col) will return something like 'EUZ...' for instance that I want to exclude. The following query does the trick, but I can't produce this via Linq-to-SQL. There seems to be no translation for the isnumeric() function in SQL Server. select max(col) from table where col like 'EU%' and 1=isnumeric(replace(col, 'EU', '')) Writing a database function, stored procedure, or anything else of that nature is far down the list of my preferred solutions, because this table is central to my app and I cannot easily replace the table object with something else. What's the next-best solution?

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