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  • Get the ranking of highest score with earliest timestamp

    - by Billy
    I have the following records: name score Date Billy 32470 12/18/2010 7:26:35 PM Sally 1100 12/19/2010 12:00:00 AM Kitty 1111 12/21/2010 12:00:00 AM Sally 330 12/21/2010 8:23:34 PM Daisy 32460 12/22/2010 3:10:09 PM Sally 32460 12/23/2010 4:51:11 PM Kitty 32440 12/24/2010 12:00:27 PM Billy 32460 12/24/2010 12:11:36 PM I want to get the leaderboard of the highest score with earliest time stamp using LINQ. In this case, the correct one is rank name 1 Billy 2 Daisy 3 Sally I use the following query: var result = (from s in Submissions group s by s.name into g orderby g.Max(q => q.Score) descending,g.Min(q => q.Date) ascending select new ScoreRecord { name = g.Key Score = g.Max(q => q.Score) }).Take(3).ToList(); I get the following wrong result: rank name 1 Billy 2 Sally 3 Daisy What's the correct linq query in this case?

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  • How can I run NHibenate queries asynchronously?

    - by andrey-tsykunov
    Hello, One way to increase scalability of the server application is to run IO-bound operation (reading files, sockets, web requests, database requests etc) asynchronously. This does not mean run then in the ThreadPool which will just block threads while operation is being executed. The correct way is to use asynchronous API (BeginRead, BeginGetResponse, BeginExecuteReader etc). The problem is well described in CLR vi C# book. Here is some article about asynchronous queries in Linq to SQL. Are any ways to execute Nhibernate query asynchonously? What about Linq to NHibernate? Thank you, Andrey

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  • How can I set MAXLENGTH on input fields automatically?

    - by Gary McGill
    I'm using ASP.NET MVC RC2. I have a set of classes that were auto-generated "Linq-to-SQL Classes", where each class models a table in my database. I have some default "edit" views that use the neat-o Html.TextBoxFor helper extension to render HTML input fields for the columns in a table. However, I notice that there is no MAXLENGTH attribute specified in the generated HTML. A quick google shows that you can add explicit attributes using TextBoxFor etc. but that would mean that I need to hard-code the values (and I need to remember to do it for every input). This seems pretty poor, considering that everything was automatically generated directly from the DB, so the size of the columns is known. (Although, to be fair, the web-side stuff has to work with any model objects, not just with Linq-to-SQL objects). Is there any nice way of getting this to do the right thing?

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  • Will this safely delete my record?

    - by Sergio Tapia
    I hate these three tables that. Two tables have a many to many relationship and as such it generates a third table. I'm using Linq-to-SQL and in the .dbml file I've dragged all the folder there to the graphic surface. Here is the method I'm using to delete an Area safely. Remember that documents are associated to an Area, so I can't just delete it and leave documents hanging. ScansDataContext db = new ScansDataContext(); /// <summary> /// Deletes an Area object from the database along with all associations in the database. /// </summary> /// <param name="area">Area object to save</param> public void Delete(Area area) { db.DocumentAreaRelations.DeleteAllOnSubmit(area.DocumentAreaRelations); db.Areas.DeleteOnSubmit(area); db.SubmitChanges(System.Data.Linq.ConflictMode.FailOnFirstConflict); }

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  • DBLinq not generating where clause

    - by sipwiz
    I'm testing out DBLinq-0.18 and DBLinq from SVN Trunk with MySQL and Postgresql. I'm only using a very simple query but on both database DBLinq is not generating a Where clause. I have confirmed this by turning on statement logging on Postgresql to check exactly what request DBLinq is sending. My Linq query is: MyDB db = new MyDB(new NpgsqlConnection("Database=database;Host=localhost;User Id=postgres;Password=password")); var customers = from customer in db.Customers where customer.CustomerUserName == "test" select customer; The query works ok but the SQL generated by DBLinq is of the form: select customerusername, customerpassword .... from public.customers There is no Where clause which means DBLinq must be pulling the whole table down before running the Linq query. Has anyone had any experience with DBLinq and know what I could be doing wrong?

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  • how to convert datetime to string in linqtosql?

    - by kwon
    I am using linqtosql and inside of linq query, I tried to convert datetime type column to string like 'dd-MM-yy'. However, I got error as following : NotSupportedException: Method 'System.String ToString(System.String)' has no supported translation to SQL. following is my linq query : from ffv in Flo_flowsheet_values where ffv.Flowsheet_key == 2489 && ffv.Variable_key == 70010558 && ffv.Status == 'A' && ffv.Column_time >= DateTime.ParseExact("2010-06-13 00:00", "yyyy-MM-dd HH:mm", null) && ffv.Column_time <= DateTime.ParseExact("2010-06-13 22:59", "yyyy-MM-dd HH:mm", null) select new { ColumnTime = ffv.Column_time ,ColumnTimeForXCategory = ffv.Column_time.Value.ToString("dd-MM-yy") ***====> this statement invoke error*** ,BTValue = Convert.ToDouble( ffv.Value) } what is problem? Thanks in advance

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  • Problems finding classes in namespace

    - by Matt
    I am trying to find all of the types in the Models namespace within an ASP.NET MVC assembly from within a testing assembly. I was trying to use LINQ to find the relevant set for me but it is returning an empty set on me. I am sure it is some simple mistake, I am still relatively new to LINQ admittedly. var abstractViewModelType = typeof (AbstractViewModel); var baseAssembly = Assembly.GetAssembly(abstractViewModelType); var modelTypes = baseAssembly.GetTypes() .Where(assemblyType => (assemblyType.Namespace.EndsWith("Models") && assemblyType.Name != "AbstractViewModel")) .Select(assemblyType => assemblyType); foreach(var modelType in modelTypes) { //Assert some things } When I reach the foreach I receive a Null reference exception.

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  • NHibernate with or without Repository

    - by Groo
    There are several similar questions on this matter, by I still haven't found enough reasons to decide which way to go. The real question is, is it reasonable to abstract the NHibernate using a Repository pattern, or not? It seems that the only reason behind abstracting it is to leave yourself an option to replace NHibernate with a different ORM if needed. But creating repositories and abstracting queries seems like adding yet another layer, and doing much of the plumbing by hand. One option is to use expose IQueryable<T> to the business layer and use LINQ, but from my experience LINQ support is still not fully implemented in NHibernate (queries simply don't always work as expected, and I hate spending time on debugging a framework). Although referencing NHibernate in my business layer hurts my eyes, it is supposed to be an abstraction of data access by itself, right? What are you opinions on this?

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  • C#: access a class property when the property identifier is known as a string

    - by Hans
    Hi, I'm using LINQ to Entities on a database which structure is not known in advance. I use reflection to retrieve the information, and now have a list of strings with all the table names. Because I use LINQ, I also have the datasource encapsulated in a C# class (linqContext), with each table being a property of that class. What I want to achieve is this: Assume one of the strings in the table names list is "Employees". This is known in code, I want to do the following: linqContext.Employees.DoSomethingHere(); Is this possible? I know that if all the propertie were just items in a list, I could use the string as indexer, linqContext["Employees"]. However, this is not the case :(

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  • Multiple Inheritance in LINQtoSQL?

    - by Bumble Bee
    Guys, I have been surfing thru the web to find a way that I could use Multiple-Table-Inheritance in LINQ-To-SQL. But it looks like that it only supports single table inheritance which is not the best way to achieve inheritance in a ORM framework. I got to read that this will be addressed in next LINQ and Entity framework implementations. But how longer a stay we are talking about? In the meantime, if any of you guys have tried out a work-around implementation to achieve this, please let me know. And I thought of using my leisure time to come up with such an implementation so suggestions are welcome! /Bumble Bee

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  • MSDTC Distributed Transaction Coordinator Enabling

    - by Curtis White
    I've a web server and a separate SQL server. I'm trying to use transaction scope to ensure that SQL queries are completed with my linq queries. I wrap everything with this using (TransactionScope scope = new TransactionScope()) I want to know where I need to install DTC. Do I need to install it on the IIS 7.5 box AND the SQL server? Do I need to unblock some ports? Are there any security risk in doing so? I've setup this up once before but don't remember how. If I can't get access to DTC then is there any other way to ensure a lINQ and sql query is atomic?

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  • InvalidOperationException sequence contains more than one element even when only one element

    - by user310256
    I have three tables, tblCompany table, tblParts table and a link table between them tblLinkCompanyParts. Since tblLinkCompanyParts is a link table so the columns that it has are LinkCompanyPartID(primary key), CompanyID from tblCompany table and PartID from tblParts as foreign keys. I have tied them up in the dbml file. In code if I write LinkCompanyParts.Parts (where LinkCompanyParts is an object of the tblLinkCompanyParts type) to get to the corresponding Part object I get the "InvalidOperationException: Sequence constains more than one element". I have looked at the data in the database and there is only one Parts record associated with the LinkCompanyPartID. The stack trace reads like at System.Linq.Enumerable.SingleOrDefault[TSource](IEnumerable`1 source) at System.Data.Linq.EntityRef`1.get_Entity() at ... I read about SingleOrDefault vs FirstOrDefault but since the link table should have a one-one mapping therefore I think SingleOrDefault should work and besides "SingleOrDefault" statement is being generated behind the scenes in the designer.cs file at the following line return this._Part.Entity; Any ideas?

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  • Multi-tier applications using L2S, WCF and Base Class

    - by Gena Verdel
    Hi all. One day I decided to build this nice multi-tier application using L2S and WCF. The simplified model is : DataBase-L2S-Wrapper(DTO)-Client Application. The communication between Client and Database is achieved by using Data Transfer Objects which contain entity objects as their properties. abstract public class BaseObject { public virtual IccSystem.iccObjectTypes ObjectICC_Type { get { return IccSystem.iccObjectTypes.unknownType; } } [global::System.Data.Linq.Mapping.ColumnAttribute(Storage = "_ID", AutoSync = AutoSync.OnInsert, DbType = "BigInt NOT NULL IDENTITY", IsPrimaryKey = true, IsDbGenerated = true)] [global::System.Runtime.Serialization.DataMemberAttribute(Order = 1)] public virtual long ID { //get; //set; get { return _ID; } set { _ID = value; } } } [DataContract] public class BaseObjectWrapper<T> where T : BaseObject { #region Fields private T _DBObject; #endregion #region Properties [DataMember] public T Entity { get { return _DBObject; } set { _DBObject = value; } } #endregion } Pretty simple, isn't it?. Here's the catch. Each one of the mapped classes contains ID property itself so I decided to override it like this [global::System.Data.Linq.Mapping.TableAttribute(Name="dbo.Divisions")] [global::System.Runtime.Serialization.DataContractAttribute()] public partial class Division : INotifyPropertyChanging, INotifyPropertyChanged { [global::System.Data.Linq.Mapping.ColumnAttribute(Storage="_ID", AutoSync=AutoSync.OnInsert, DbType="BigInt NOT NULL IDENTITY", IsPrimaryKey=true, IsDbGenerated=true)] [global::System.Runtime.Serialization.DataMemberAttribute(Order=1)] public override long ID { get { return this._ID; } set { if ((this._ID != value)) { this.OnIDChanging(value); this.SendPropertyChanging(); this._ID = value; this.SendPropertyChanged("ID"); this.OnIDChanged(); } } } } Wrapper for division is pretty straightforward as well: public class DivisionWrapper : BaseObjectWrapper<Division> { } It worked pretty well as long as I kept ID values at mapped class and its BaseObject class the same(that's not very good approach, I know, but still) but then this happened: private CentralDC _dc; public bool UpdateDivision(ref DivisionWrapper division) { DivisionWrapper tempWrapper = division; if (division.Entity == null) { return false; } try { Table<Division> table = _dc.Divisions; var q = table.Where(o => o.ID == tempWrapper.Entity.ID); if (q.Count() == 0) { division.Entity._errorMessage = "Unable to locate entity with id " + division.Entity.ID.ToString(); return false; } var realEntity = q.First(); realEntity = division.Entity; _dc.SubmitChanges(); return true; } catch (Exception ex) { division.Entity._errorMessage = ex.Message; return false; } } When trying to enumerate over the in-memory query the following exception occurred: Class member BaseObject.ID is unmapped. Although I'm stating the type and overriding the ID property L2S fails to work. Any suggestions?

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  • SQL to get range of results in alphabetical order

    - by Tom Gullen
    I have a table, tblTags which works in much the same way as StackOverflows tagging system. When I view a tags page, let's say the tag Tutorial I want to display the 10 tags before and after it in alphabetical order. So if we are given the tag Tutorial of ID 30 how can we return a record set in the order resembling: Tap Tart > Tutorial Umbrellas Unicorns Xylaphones I have thought of ways of doing this, badly, in my opinion as they involve retrieving ugly amounts of data. I'm not sure if it's possible to do something along the lines of (pseudo): SELECT RANGE(0 - 30) FROM tblTags ORDER BY Name ASC But how do you know the position of the tutorial tag in the list in an efficient manner without traversing the entire list until you find it? I'm using SQL Server 2008 R2 Express with LINQ if it makes any difference, SQL queries or LINQ would be great answers, thanks!

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  • what is a fast way to output h5py dataset to text?

    - by user362761
    I am using the h5py python package to read files in HDF5 format. (e.g. somefile.h5) I would like to write the contents of a dataset to a text file. For example, I would like to create a text file with the following contents: 1,20,31,75,142,324,78,12,3,90,8,21,1 I am able to access the dataset in python using this code: import h5py f = h5py.File('/Users/Me/Desktop/thefile.h5', 'r') group = f['/level1/level2/level3'] dset = group['dsetname'] My naive approach is too slow, because my dataset has over 20000 entries: # write all values to file for index in range(len(dset)): # do not add comma after last value if index == len(dset)-1: txtfile.write(repr(dset[index])) else: txtfile.write(repr(dset[index])+',') txtfile.close() return None Is there a faster way to write this to a file? Perhaps I could convert the dataset into a NumPy array or even a Python list, and then use some file-writing tool? (I could experiment with concatenating the values into a larger string before writing to file, but I'm hoping there's something entirely more elegant)

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  • Is it weird or strange to make multiple WCF Calls to build a ViewModel before presenting it?

    - by Nate Bross
    Am I doing something wrong if I need code like this in a Controller? Should I be doing something differently? public ActionResult Details(int id) { var svc = new ServiceClient(); var model = new MyViewModel(); model.ObjectA = svc.GetObjectA(id); model.ObjectB = svc.GetObjectB(id); model.ObjectC = svc.GetObjectC(id); return View(model); } The reason I ask, is because I've got Linq-To-Sql on the back end and a WCF Service which exposes functionality through a set of DTOs which are NOT the Linq-To-Sql generated classes and thus do not have the parent/child properties; but in the detail view, I would like to see some of the parent/child data.

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  • How To Query Many-to-Many Table (one table's values becomes column headers)

    - by CRice
    Given this table structure, I want to flatten out the many-to-many relationships and make the values in the Name field of one table into column headers and the quantities from the same table into column values. The current idea which will work is to put the values into a Dictionary (hashtable) and represent this data in code but im wondering if there is a SQL way to do this. I am also using Linq-to-SQL for data access so a Linq-to-SQL solution would be ideal. [TableA] (int Id) [TableB] (int id, string Name) [TableAB] (int tableAId, int tableBId, int Quantity) fk: TableA.Id joins to TableAB.tableAId fk: TableB.Id joins to TableAB.tableBId Is there a way I can query the three tables and return one result for example: TableA [Id] 1 TableB [Id], [Name] 1, "Red" 2, "Green" 3, "Blue" TableAB [TableAId], [TableBId], [Quantity] 1 1 5 1 2 6 1 3 7 Query Result: [TableA.Id], [Red], [Green], [Blue] 1, 5, 6, 7

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  • MVC C# Controller Method to return Tables

    - by Rob Tiu
    I'm a real beginner with MVC and my issue is this, I have a mdf database with multiple tables and I want to have a method return "ANY" table from the database and pass it to a aspx view. Examples of other tables in the database: Articles, Products, Supplies Here is an example of my code to view an Article Table from the database: //USING LINQ-SQL CONTEXT DATABASE public ActionResult ArticlePage() { tinypeas_db_contextDataContext context = HttpContext.Application["context"] as tinypeas_db_contextDataContext; try { return View(context.Articles); } catch { return Json(false, JsonRequestBehavior.AllowGet); } } How would I modify this method to dynamically pass any table to the view? Or should I be using something else other than Linq-to-SQL

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  • How to get dataset to populate data into dbgrid in Delphi 6?

    - by Chris J
    I have created a DBGrid in Delphi 6 and tied it to a DataSource contained in a DataModule. The Dataset for that source in also located in the same module. In the OnShow event for the form, I activate the dataset and set a label equal to the rowcount for the dataset. This shows several hundred rows but nothing shows in the dbgrid. If I activate the dataset in the IDE, the grid populates with the expected data. Does anyone have any idea why this behaviour would change between the IDE and normal runtime? We are also using SDAC connection components. All 3rd party component choices are not mine to change. I can elaborate as necessary for clarification, but I mainly need troubleshooting ideas to start at.

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  • Typed DataSet connection - required to have one in the .xsd file?

    - by Kyralessa
    In the .xsd file for a typed DataSet in .NET, there's a <Connections> section that contains a list of any data connections I've used to set up the DataTables and TableAdapters. There are times when I'd prefer not to have those there. For instance, sometimes I prefer to pass in a connection string to a custom constructor and use that rather than look for one in settings, .config, etc. But it seems like if I remove the connection strings from that section (leaving it empty), or remove the section entirely, the DataSet code-generation tool freaks out. Whereas if I don't remove them, the DataSet gripes when I put it in a different project because it can't find the settings for those connection strings. Is there any way I can tell a typed DataSet not to worry about any connections? (Obviously I'll have to give it a connection if I change any TableAdapter SQL or stored procs, but that should be my problem.)

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  • Enumerable.Range in and Expression and Entity Framework

    - by eka808
    I'm currently developping an expression method (used in linq to entity queries) who has to give me a daycount for a given period (start date and end date) decrementing this daycount if specials days are in the period. My idea was the following : Generate an enumerable with all the dates (and with Enumerable.Range) Make a .Where on this enumerable to remove the specials dates Like a MyEnumerable.Where(a = a != "20120101") After that, return a MyEnumerable.Count() I come with this code : return (p) => Enumerable .Range(1, 4) .Where(a => a != 20120101) .AsQueryable() .Count() I tried to cast as a list, as a queryable, both (like the example) and no way ! it doesn't work ! I always get this error : LINQ to Entities does not recognize the method 'System.Collections.Generic.IEnumerable`1[System.Int32] Range(Int32, Int32)' method, and this method cannot be translated into a store expression. Have you got an idea about that ? Using an enumerable is of course not mandatory, any working solutions is good ^^ Thank's by advance !

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  • How to write back to database from Silverlight?

    - by Manoj
    Hi, I use LINQ to SQL to get data from a database and use a service contract to access it in Silverlight at the client side. I display the data in a DataGrid. Now how do I make sure that any changes in the datagrid is written back to the database? EDIT: This is the example code I implemented: http://www.silverlight.net/learn/tutorials/sqldatagrid-cs/ Here I wanted any change in the datagrid reflected back in the database. The SubmitChanges function works in the DataContext object which is: public partial class DataClasses1DataContext : System.Data.Linq.DataContext But this is not exposed in the contract and so not visible in the client side code.

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  • EF Query using .Contains() and .ToLowerInvariant() Results in no matches when match is found at the end of a string

    - by MyNameIsJob
    Is it possible to step into a linq query? I have a linq to entity framework 4 query in it's simplest form: List = List.Where(f => f.Value.ToString().ToLowerInvariant().Contains(filter.ToLowerInvariant())); It's a query against an Entity Framework DbContext and I'm having trouble seeing why it works for something like: List searching for 001 yields no results against the following list Test001 Test002 Test003 Test004 However any other search yields results (Such as t00 or Test) Update Basically I'm looking for why a query such as the above wouldn't return a result when I'm using a contains and the value matches the end of a string vs just the middle or begining. It's really confusing. OK, it appears to have something to do with ToLowerInvariant() - when I removed that method it works just fine.

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  • How do I search for an array of values in a many to many relation?

    - by Kristian Gudal
    Hey I have a problem with my LINQ to Entity model many to mant relation. I am new to both C# and LINQ, so bear with me. I have a model containing pictures and tags, where each picture can have many tags, and each tag can be on many pictures. In the db there is a normal relation table, but in the object model I see it as picture.tags (as a list) and tag.pictures (as a list). A search query contains several tags, and the result of the search is to contain all pictures that are tagged with all the tags (but maybe more) I have searched for. The number of tags to search for is not fixed. How can this best be done?

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