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  • How to perform a select using a WHERE NOT EXISTS

    - by Peter Bridger
    I'm using LINQ2SQL and I want to compare two tables and select all rows that are missing from one tables (based upon one of the column values). In standard SQL I would write this as: SELECT FirstName, LastName, RefId, Email FROM Users_ActiveDirectory AS ADU WHERE NOT EXISTS ( SELECT U.RefId FROM Users AS U WHERE U.RefID = ADU.RefId ) However I'm not sure how to achieve the same result using LINQ2SQL?

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  • How to prevent linq-to-sql designer undo my changing

    - by anonim.developer
    Dear All, Thanks for your attention in advance, I’ve met an issue with LINQ-2-SQL designer in VS 2008 SP1 which has made me CRAZY. I use Linq2sql as my DAL. It seems Linq2sql speeds up coding in the first step but lots of issues arise in feature specifically with table or object inheritance. In this case I have a class Entity that all other entity classes generated by Linq2sql designer inherit from. public abstract class Entity { public virtual Guid ID { get; protected set; } } public partial class User : monius.Data.Entity { } And the following generated by L2S designer (DataModel.designer.cs) [Column(Storage = "_ID", AutoSync = AutoSync.OnInsert, DbType = "UniqueIdentifier NOT NULL", IsPrimaryKey = true, IsDbGenerated = true, UpdateCheck = UpdateCheck.Never)] [DataMember(Order = 1)] public System.Guid ID { get { return this._ID; } set { if ((this._ID != value)) { this.OnIDChanging(value); this.SendPropertyChanging(); this._ID = value; this.SendPropertyChanged("ID"); this.OnIDChanged(); } } } When I compile the code VS warns me that Warning 1 'User.ID' hides inherited member 'Entity.ID'. To make the current member override that mplementation, add the override keyword. Otherwise add the new keyword. That warning is obvious and I have to change the code generated by L2S designer (DataModel.designer.cs) to […] public override System.Guid ID { … protected set … } And the code compiled with no error or warning and everyone is happy. But that is not the end of story. As soon as I made changes to entities of the diagram (dbml) or even I open dbml file to view it, any change manually I made to designer has been vanished and POOF! Redo AGAIN. That is a painful job. Now I wonder if there is a way to force L2S designer not changing portions of auto-generated code. I’ll be appreciated if someone kindly helps me with this issue.

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  • PerWebRequest LifetimeManager and Beyond (Asp.net Mvc)

    - by Soe Moe
    Hi, Currently, I created my custom PerWebRequestLifetimeManager using HttpContext.Current.Items as backing store. I used that lifetime manager for Linq2Sql DataContext. Eveything is working fine until I need to use Cache for storing data (for 5 min). After 5 min, I need to retrieve data from DB and put it into the Cache. To do so, I need to use Linq2Sql DataContext for retrieving data. But during that time, HttpContext.Current is null because which was happened when cache is expired; not in Web Request. So, what kind of LifetimeManager should I use for this scenario? Thanks in advance.

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  • StructureMap : How to define default constructor by code ?

    - by cik
    Hi, I can't figure out how to define the default constructor (when it exists overloads) for a type in StructureMap (version 2.5) by code. I want to get an instance of a service and the container has to inject a Linq2Sql data context instance into it. I wrote this in my 'bootstrapper' method : ForRequestedType<MyDataContext>().TheDefault.Is.OfConcreteType<MyDataContext>(); When I run my app, I got this error : StructureMap Exception Code: 202 No Default Instance defined for PluginFamily MyNamespace.Data.SqlRepository.MyDataContext, MyNamespace.Data, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null If I comment out all Linq2Sql generated contructors that I don't need, it works fine. Update : Oh, and I forgot to say that I would not use the [StructureMap.DefaultConstructor] attribute.

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  • Linq To Sql: Compiled Queries and Extension Methods

    - by Beni
    Hi community, I'm interessted, how does Linq2Sql handles a compiled query, that returns IQueryable. If I call an extension method based on a compiled query like "GetEntitiesCompiled().Count()" or "GetEntitiesCompiled().Take(x)". What does Linq2Sql do in the background? This would be very bad, so in this situation I should write a compiled query like "CountEntitiesCompiled". Does he load the result (in this case "GetEntitiesCompiled()") into the memory (mapped to the entity class like "ToList()")? So what situations make sense, when the compiled queries return IQueryable, that query is not able to modify, before request to the Sql-Server. So in my opinion I can just as good return List. Thanks for answers!

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  • Column.DbType affecting runtime behavior

    - by leppie
    Hi According to the MSDN docs, the DbType property/attribute of a Column type/element is only used for database creation. Yet, today, when trying to submit data to an IMAGE column on a SQLCE database (not sure if only on CE), I got an exception of 'Data truncated to 8000 bytes'. This was due to the DbType still being defined as VARBINARY(MAX) which SQLCE does not support. Changing the type to IMAGE in the DbType fixes the issue. So what other surprises does Linq2SQL attributes hold in store? Is this a bug or intended? Should I report it to MS? UPDATE After getting the answer from Guffa, I tested it, but it seems for NVARCHAR(10) adding a 11 char length string causes a SQL exception, and not Linq2SQL one. The data was truncated while converting from one data type to another. [ Name of function(if known) = ] A first chance exception of type 'System.Data.SqlServerCe.SqlCeException' occurred in System.Data.SqlServerCe.dll

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  • Authenticating model - best practices

    - by zerkms
    I come into ASP.NET from php so the reason why i ask my question is because it's totally different nature of how application works and handles requests. well, i have an exists table with user creditians, such as: id, login, password (sha hashed), email, phone, room i have built custom membership provider so it can handle my own database authentication schema. and now i'm confused, because User.Identity.Name contains only user's login, but not the complete object (i'm using linq2sql to communicate with database and i need in it's User object to work). at php applications i just store user object at some static method at Auth class (or some another), but here at ASP.NET MVC i cannot do this, because static member is shared across all requests and permanent, and not lives within only current request (as it was at php). so my question is: how and where should i retrieve and store linq2sql user object to work with it within current and only current request? (after request processed successfully i expect it will be disposed from memory and on next request will be created again). or i'm following totally wrong way?

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  • Using SqlServer 2008 and TSQL Subtract 1 Hour From All Values In a DateTime Column

    In this post, well go briefly the process of how you would update all rows in a SQL Server 2008 table such that a particular date column will be moved back 1 hour in time.  This is actually pretty simple, but being that I typically do my work in the ORM layer (that is LINQ2SQL [...]...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • How to populate a generic list of objects in C# from SQL database

    - by developr
    I am just learning ASP.NET c# and trying to incorporate best practices into my applications. Everything that I read says to layer my applications into DAL, BLL, UI, etc based on separation of concerns. Instead of passing datatables around, I am thinking about using custom objects so that I am loosely coupled to my data layer and can take advantage of intellisense in VS. I assume these objects would be considered DTOs? First, where do these objects reside in my layers? BLL, DAL, other? Second, when populating from SQL, should I loop through a data reader to populate the list or first fill a data table, then loop through the table to populate the list? I know you should close the database connection as soon as possible, but it seems like even more overhead to populate the data table and then loop through that for the list. Third, everything I see these days says use Linq2SQL. I am planning to learn Linq2SQL, but at this time I am working with a legacy database that doesn't have foreign keys setup and I do not have the ability to fix it atm. Also, I want to learn more about c# before I start getting into ORM solutions like nHibernate. At the same time I don't want to type out all the connection and SQL plumbing for every query. Is it ok to use the Enterprise DAAB for now?

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  • ORM Persistence by Reachability violates Aggregate Root Boundaries?

    - by Johannes Rudolph
    Most common ORMs implement persistence by reachability, either as the default object graph change tracking mechanism or an optional. Persistence by reachability means the ORM will check the aggregate roots object graph and determines wether any objects are (also indirectly) reachable that are not stored inside it's identity map (Linq2Sql) or don't have their identity column set (NHibernate). In NHibernate this corresponds to cascade="save-update", for Linq2Sql it is the only supported mechanism. They do both, however only implement it for the "add" side of things, objects removed from the aggregate roots graph must be marked for deletion explicitly. In a DDD context one would use a Repository per Aggregate Root. Objects inside an Aggregate Root may only hold references to other Aggregate Roots. Due to persistence by reachability it is possible this other root will be inserted in the database event though it's corresponding repository wasn't invoked at all! Consider the following two Aggregate Roots: Contract and Order. Request is part of the Contract Aggregate. The object graph looks like Contract->Request->Order. Each time a Contractor makes a request, a corresponding order is created. As this involves two different Aggregate Roots, this operation is encapsulated by a Service. //Unit Of Work begins Request r = ...; Contract c = ContractRepository.FindSingleByKey(1); Order o = OrderForRequest(r); // creates a new order aggregate r.Order = o; // associates the aggregates c.Request.Add(r); ContractRepository.SaveOrUpdate(c); // OrderAggregate is reachable and will be inserted Since this Operation happens in a Service, I could still invoke the OrderRepository manually, however I wouldn't be forced to!. Persistence by reachability is a very useful feature inside Aggregate Roots, however I see no way to enforce my Aggregate Boundaries.

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  • Linq 2 SQL Store inherited classes - not mapped to tables in the database

    - by user348672
    Hi. I'm trying to introduce the Linq2SQL technique into the project and have encountered the following issue: I've created ORM classes based on the Northwind database. In some other application I create several classes derived from the Linq2SQL classes. I'm able to add such a class to EntitySet but the application fails to submit changes. Is there any way around this? Sample code(MyClass is derived from the Order): DataClasses1DataContext northwind = new DataClasses1DataContext(); Product chai = northwind.Products.Single(p => p.ProductName == "Chai"); Product tofu = northwind.Products.Single(p => p.ProductName == "Tofu"); Order myOrder = new Order(); myOrder.OrderDate = DateTime.Now; myOrder.RequiredDate = DateTime.Now.AddDays(1); myOrder.Freight = 34; Order_Detail myItem1 = new Order_Detail(); myItem1.Product = chai; myItem1.Quantity = 12345; Order_Detail myItem2 = new Order_Detail(); myItem2.Product = tofu; myItem2.Quantity = 3; myOrder.Order_Details.Add(myItem1); myOrder.Order_Details.Add(myItem2); Customer myCustomer = northwind.Customers.Single(c => c.CompanyName == "B's Beverages"); MyClass newOrder = new MyClass(); newOrder.OrderDate = DateTime.Now; newOrder.RequiredDate = DateTime.Now.AddDays(31); newOrder.Freight = 35; Order_Detail myItem3 = new Order_Detail(); myItem3.Product = tofu; myItem3.Quantity = 3; newOrder.Order_Details.Add(myItem3); myCustomer.Orders.Add(myOrder); myCustomer.Orders.Add(newOrder); As I said I'm able to add the newOrder object but unable to submit into the database.

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  • Advice Please: SQL Server Identity vs Unique Identifier keys when using Entity Framework

    - by c.batt
    I'm in the process of designing a fairly complex system. One of our primary concerns is supporting SQL Server peer-to-peer replication. The idea is to support several geographically separated nodes. A secondary concern has been using a modern ORM in the middle tier. Our first choice has always been Entity Framework, mainly because the developers like to work with it. (They love the LiNQ support.) So here's the problem: With peer-to-peer replication in mind, I settled on using uniqueidentifier with a default value of newsequentialid() for the primary key of every table. This seemed to provide a good balance between avoiding key collisions and reducing index fragmentation. However, it turns out that the current version of Entity Framework has a very strange limitation: if an entity's key column is a uniqueidentifier (GUID) then it cannot be configured to use the default value (newsequentialid()) provided by the database. The application layer must generate the GUID and populate the key value. So here's the debate: abandon Entity Framework and use another ORM: use NHibernate and give up LiNQ support use linq2sql and give up future support (not to mention get bound to SQL Server on DB) abandon GUIDs and go with another PK strategy devise a method to generate sequential GUIDs (COMBs?) at the application layer I'm leaning towards option 1 with linq2sql (my developers really like linq2[stuff]) and 3. That's mainly because I'm somewhat ignorant of alternate key strategies that support the replication scheme we're aiming for while also keeping things sane from a developer's perspective. Any insight or opinion would be greatly appreciated.

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  • Linq generic Expression in query on "element" or on IQueryable (multiple use)

    - by Bogdan Maxim
    Hi, I have the following expression public static Expression<Func<T, bool>> JoinByDateCheck<T>(T entity, DateTime dateToCheck) where T : IDateInterval { return (entityToJoin) => entityToJoin.FromDate.Date <= dateToCheck.Date && (entityToJoin.ToDate == null || entityToJoin.ToDate.Value.Date >= dateToCheck.Date); } IDateInterval interface is defined like this: interface IDateInterval { DateTime FromDate {get;} DateTime? ToDate {get;} } and i need to apply it in a few ways: (1) Query on Linq2Sql Table: var q1 = from e in intervalTable where FunctionThatCallsJoinByDateCheck(e, constantDateTime) select e; or something like this: intervalTable.Where(FunctionThatCallsJoinByDateCheck(e, constantDateTime)) (2) I need to use it in some table joins (as linq2sql doesn't provide comparative join): var q2 = from e1 in t1 join e2 in t2 on e1.FK == e2.PK where OtherFunctionThatCallsJoinByDateCheck(e2, e1.FromDate) or var q2 = from e1 in t1 from e2 in t2 where e1.FK == e2.PK && OtherFunctionThatCallsJoinByDateCheck(e2, e1.FromDate) (3) I need to use it in some queries like this: var q3 = from e in intervalTable.FilterFunctionThatCallsJoinByDateCheck(constantDate); Dynamic linq is not something that I can use, so I have to stick to plain linq. Thank you Clarification: Initially I had just the last method (FilterFunctionThatCallsJoinByDateCheck(this IQueryable<IDateInterval> entities, DateTime dateConstant) ) that contained the code from the expression. The problem is that I get a SQL Translate exception if I write the code in a method and call it like that. All I want is to extend the use of this function to the where clause (see the second query in point 2)

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  • LINQ to SQL - Insert yielding strange behavior.

    - by Isaac
    Hi, I'm trying to insert several newly created items to the database. I have a LINQ2SQL generated class called "Order". Inside order, there's a property called "OrderItems" which is also generated by LINQ2SQL and represents the Items of that Order. So far so good. The problem I'm having right now, is when I try to add more than one newly created OrderItem inside Order. I.E: Order o = orderWorker.GetById( 10 ); for( int i=0; i < 5; ++i ) { OrderItem oi =new OrderItem { Order = order, Price = 100, ShippingPrice = 100, ShippingMethod = ... }; o.OrderItems.Add( oi ); } context.SubmitChanges(); Unfortunately, only a single entity is being added. Yes, I checked the generated SQL by adding Context.Log = Console.Out, and yes, only one statement was created. Any clues? By the way I know I'm not using InsertOnSubmit, by the documentation says: You can explicitly request Inserts by using InsertOnSubmit. Alternatively, LINQ to SQL can infer Inserts by finding objects connected to one of the known objects that must be updated. For example, if you add an Untracked object to an EntitySet(TEntity) or set an EntityRef(TEntity) to an Untracked object, you make the Untracked object reachable by way of tracked objects in the graph. While processing SubmitChanges, LINQ to SQL traverses the tracked objects and discovers any reachable persistent objects that are not tracked. Such objects are candidates for insertion into the database. Thank you very much for your time.

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  • Application that depends heavily on stored procedures

    - by PieterG
    We currently have an application that depends largely on stored procedures. There is a heavy use of temp tables. It's an extremely large application. Facing this situation, I would like to use Entity Framework or Linq2Sql for a rewrite. I might consider using Fluent Hibernate or Subsonic, as i've used them quite extensively in the past. I've had problems with Linq2Sql generating the return types for the stored procedures because of the usage of the temp tables, and I think it's cumbersome to go and change all the stored procedures from temp tables to in-memory tables. Considering the 2 choices that I want to make, which one of the 2 is the best route to go and why? If my choices are extremely idiotic, please provide alternatives. Edit: The reason for the question and the change is that the data access layer is non-existent and was built 10 years ago. We currently still run into a lot of issues with it. I don't want to divulge too much, but if you saw it, your eyes would start bleeding :)

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  • Eager Loading more than 1 table in LinqtoSql

    - by Michael Freidgeim
    When I've tried in Linq2Sql to load table with 2 child tables, I've noticed, that multiple SQLs are generated. I've found that  it isa known issue, if you try to specify more than one to pre-load it just  picks which one to pre-load and which others to leave deferred (simply ignoring those LoadWith hints)There are more explanations in http://codebetter.com/blogs/david.hayden/archive/2007/08/06/linq-to-sql-query-tuning-appears-to-break-down-in-more-advanced-scenarios.aspxThe reason the relationship in your blog post above is generating multiple queries is that you have two (1:n) relationship (Customers->Orders) and (Orders->OrderDetails). If you just had one (1:n) relationship (Customer->Orders) or (Orders->OrderDetails) LINQ to SQL would optimize and grab it in one query (using a JOIN).  The alternative -to use SQL and POCO classes-see http://stackoverflow.com/questions/238504/linq-to-sql-loading-child-entities-without-using-dataloadoptions?rq=1Fortunately the problem is not applicable to Entity Framework, that we want to use in future development instead of Linq2SqlProduct firstProduct = db.Product.Include("OrderDetail").Include("Supplier").First(); ?

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  • Is there something better than a StringBuilder for big blocks of SQL in the code

    - by Eduardo Molteni
    I'm just tired of making a big SQL statement, test it, and then paste the SQL into the code and adding all the sqlstmt.append(" at the beginning and the ") at the end. It's 2011, isn't there a better way the handle a big chunk of strings inside code? Please: don't suggest stored procedures or ORMs. edit Found the answer using XML literals and CData. Thanks to all the people that actually tried to answer the question without questioning me for not using ORM, SPs and using VB edit 2 the question leave me thinking that languages could try to make a better effort for using inline SQL with color syntax, etc. It will be cheaper that developing Linq2SQL. Just something like: dim sql = <sql> SELECT * ... </sql>

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  • Sql Server Data Tools & Entity Framework - is there any synergy here?

    - by Benjol
    Coming out of a project using Linq2Sql, I suspect that the next (bigger) one might push me into the arms of Entity Framework. I've done some reading-up on the subject, but what I haven't managed to find is a coherent story about how SQL Server Data Tools and Entity Framework should/could/might be used together. Were they conceived totally separately, and using them together is stroking the wrong way? Are they somehow totally orthogonal and I'm missing the point? Some reasons why I think I might want both: SSDT is great for having 'compiled' (checked) and easily versionable sql and schema But the SSDT 'migration/update' story is not convincing (to me): "Update anything" works ok for schema, but there's no way (AFAIK) that it can ever work for data. On the other hand, I haven't tried the EF migration to know if it presents similar problems, but the Up/Down bits look quite handy.

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  • Silverlight 4 + RIA Services - Ready for Business: Exposing Data from Entity Framework

    To continue our series I wanted to look next at how to expose your data from the server side of your application.  The interesting data in your business applications come from a wide variety of data sources.  From a SQL Database, from Oracle DB, from Sql Azure, from Sharepoint, from a mainframe and you have likely already chosen a datamodel such as NHibernate, Linq2Sql, Entity Framework, Stored Proc, a service.   The goal of RIA Service in this release is to make it easy to...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • Linq 2 SQL One to Zero or One relationship possible?

    - by Mr. Flibble
    Is it possible to create a one to zero or one relationship in Linq2SQL? My understanding is that to create a one to one relationship you create a FK relationship on the PK of each table. But you cannot make the PK nullable, so I don't see how to make a one to zero or one relationship work? I'm using the designer to automatically create the model - so I would like to know how to set up the SQL tables to induce the relationship - not some custom ORM code.

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  • Linq-to-SQL Grouping not ordering correctly

    - by Grant
    Hi can someone help me convert this tsql statement into c# linq2sql? select [series] from table group by [series] order by max([date]) desc This is what i have so far - the list is not in correct order.. var x = from c in db.Table orderby c.Date descending group c by c.Series into d select d.Key;

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  • Removing table prefixes on ASP.NET MVC DataModel entities

    - by Tim Shults
    My database tables have prefixes on them and when the DataModel generates the EntityObjects they have the prefixes at the beginning of the class name. Is there anyway that I can have those prefixes ignored when the DataModel is updating/creating the classes? I've found the below question, but with no solution. http://stackoverflow.com/questions/1800065/removing-table-prefix-in-linq2sql-setup/2525827#2525827 Thanks in advance, Tim Shults

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  • .NET JIT Code Cache leaking?

    - by pitchfork
    We have a server component written in .Net 3.5. It runs as service on a Windows Server 2008 Standard Edition. It works great but after some time (days) we notice massive slowdowns and an increased working set. We expected some kind of memory leak and used WinDBG/SOS to analyze dumps of the process. Unfortunately the GC Heap doesn’t show any leak but we noticed that the JIT code heap has grown from 8MB after the start to more than 1GB after a few days. We don’t use any dynamic code generation techniques by our own. We use Linq2SQL which is known for dynamic code generation but we don’t know if it can cause such a problem. The main question is if there is any technique to analyze the dump and check where all this Host Code Heap blocks that are shown in the WinDBG dumps come from? [Update] In the mean time we did some more analysis and had Linq2SQL as probable suspect, especially since we do not use precompiled queries. The following example program creates exactly the same behaviour where more and more Host Code Heap blocks are created over time. using System; using System.Linq; using System.Threading; namespace LinqStressTest { class Program { static void Main(string[] args) { for (int i = 0; i < 100; ++ i) ThreadPool.QueueUserWorkItem(Worker); while(runs < 1000000) { Thread.Sleep(5000); } } static void Worker(object state) { for (int i = 0; i < 50; ++i) { using (var ctx = new DataClasses1DataContext()) { long id = rnd.Next(); var x = ctx.AccountNucleusInfos.Where(an => an.Account.SimPlayers.First().Id == id).SingleOrDefault(); } } var localruns = Interlocked.Add(ref runs, 1); System.Console.WriteLine("Action: " + localruns); ThreadPool.QueueUserWorkItem(Worker); } static Random rnd = new Random(); static long runs = 0; } } When we replace the Linq query with a precompiled one, the problem seems to disappear.

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