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• Adding more attributes to linq to sql entity

  - by jess

  Hi, I want to add browsable attribute to some properties for entities generated by linq-to-sql.Is it a good idea? Since,these entities are auto-generated,and when I regenerate they(the attributes I have added) might be overwritten

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• Linq to entity select items and give id

  - by GodSmart

  I have a table example you can see below ID Name Value 3 NameOne ValueOne 7 NameTwo ValueTwo 10 NameThree ValueThree I need to select with Linq to Entity and get results as you can see in example below: ItemID ItemName 1 NameOne 2 NameTwo 3 NameThree

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• Framework 4 Features: Summary of Security enhancements

  - by Anthony Shorten

  In the last log entry I mentioned one of the new security features in Oracle Utilities Application Framework 4.0.1. Security is one of the major "tent poles" (to borrow a phrase from Steve Jobs) in this release of the framework. There are a number of security related enhancements requested by customers and as a result of internal reviews that we have introduced. Here is a summary of some of the security enchancements we have added in this release: Security Cache Changes - Security authorization information is automatically cached on the server for performance reasons (security is checked for every single call the product makes for all modes of access). Prior to this release the cache auto-refreshed every 30 minutes (or so). This has beem made more nimble by supporting a cache refresh every minute (or so). This means authorization changes are reflected quicker than before. Business Level security - Business Services are configurable services that are based upon Application Services. Typically, the business service inherited its security profile from its parent service. Whilst this is sufficient for most needs, it is now required to further specify security on the Business Service definition itself. This will allow granular security and allow the same application service to be exposed as different Business Services with their own security. This is particularly useful when you base a Business Service on a query zone. User Propogation - As with other client server applications, the database connections are pooled and shared as needed. This means that a common database user is used to access the database from the pool to allow sharing. Unfortunently, this means that tracability at the database level is that much harder. In Oracle Utilities Application Framework V4 the end userid is now propogated to the database using the CLIENT_IDENTIFIER as part of the Oracle JDBC connection API. This not only means that the common database userid is still used but the end user is indentifiable for the duration of the database call. This can be used for monitoring or to hook into Oracle's database security products. This enhancement is only available to Oracle Database customers. Enhanced Security Definitions - Security Administrators use the product browser front end to control access rights of defined users. While this is sufficient for most sites, a new security portal has been introduced to speed up the maintenance of security information. Oracle Identity Manager Integration - With the popularity of Oracle's Identity Management Suite, the Framework now provides an integration adapter and Identity Manager Generic Transport Connector (GTC) to allow users and group membership to be provisioned to any Oracle Utilities Application Framework based product from Oracle's Identity Manager. This is also available for Oracle Utilties Application Framework V2.2 customers. Refer to My Oracle Support KBid 970785.1 - Oracle Identity Manager Integration Overview. Audit On Inquiry - Typically the configurable audit facility in the Oracle Utilities Application Framework is used to audit changes to records. In Oracle Utilities Application Framework the Business Services and Service Scripts could be configured to audit inquiries as well. Now it is possible to attach auditing capabilities to zones on the product (including base package ones). Time Zone Support - In some of the Oracle Utilities Application Framework based products, the timezone of the end user is a factor in the processing. The user object has been extended to allow the recording of time zone information for use in product functionality. JAAS Suport - Internally the Oracle Utilities Application Framework uses a number of techniques to validate and transmit security information across the architecture. These various methods have been reconciled into using Java Authentication and Authorization Services for standardized security. This is strictly an internal change with no direct on how security operates externally. JMX Based Cache Management - In the last bullet point, I mentioned extra security applied to cache management from the browser. Alternatively a JMX based interface is now provided to allow IT operations to control the cache without the browser interface. This JMX capability can be initiated from a JSR120 compliant JMX console or JMX browser. I will be writing another more detailed blog entry on the JMX enhancements as it is quite a change and an exciting direction for the product line. Data Patch Permissions - The database installer provided with the product required lower levels of security for some operations. At some sites they wanted the ability for non-DBA's to execute the utilities in a controlled fashion. The framework now allows feature configuration to allow delegation for patch execution. User Enable Support - At some sites, the use of temporary staff such as contractors is commonplace. In this scenario, temporary security setups were required and used. A potential issue has arisen when the contractor left the company. Typically the IT group would remove the contractor from the security repository to prevent login using that contractors userid but the userid could NOT be removed from the authorization model becuase of audit requirements (if any user in the product updates financials or key data their userid is recorded for audit purposes). It is now possible to effectively diable the user from the security model to prevent any use of the useridwhilst retaining audit information. These are a subset of the security changes in Oracle Utilities Application Framework. More details about the security capabilities of the product is contained in My Oracle Support KB Id 773473.1 - Oracle Utilities Application Framework Security Overview.

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• Use CompiledQuery.Compile to improve LINQ to SQL performance

  - by Michael Freidgeim

  After reading DLinq (Linq to SQL) Performance and in particular Part 4  I had a few questions. If CompiledQuery.Compile gives so much benefits, why not to do it for all Linq To Sql queries? Is any essential disadvantages of compiling all select queries? What are conditions, when compiling makes whose performance, for how much percentage? World be good to have default on application config level or on DBML level to specify are all select queries to be compiled? And the same questions about Entity Framework CompiledQuery Class. However in comments I’ve found answer  of the author ricom 6 Jul 2007 3:08 AM Compiling the query makes it durable. There is no need for this, nor is there any desire, unless you intend to run that same query many times. SQL provides regular select statements, prepared select statements, and stored procedures for a reason.  Linq now has analogs. Also from 10 Tips to Improve your LINQ to SQL Application Performance   If you are using CompiledQuery make sure that you are using it more than once as it is more costly than normal querying for the first time. The resulting function coming as a CompiledQuery is an object, having the SQL statement and the delegate to apply it.  And your delegate has the ability to replace the variables (or parameters) in the resulting query. However I feel that many developers are not informed enough about benefits of Compile. I think that tools like FxCop and Resharper should check the queries  and suggest if compiling is recommended. Related Articles for LINQ to SQL: MSDN How to: Store and Reuse Queries (LINQ to SQL) 10 Tips to Improve your LINQ to SQL Application Performance Related Articles for Entity Framework: MSDN: CompiledQuery Class Exploring the Performance of the ADO.NET Entity Framework - Part 1 Exploring the Performance of the ADO.NET Entity Framework – Part 2 ADO.NET Entity Framework 4.0: Making it fast through Compiled Query

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• LINQ - Select Statement - The null value cannot be assigned to a member with type System.Int32 which

  - by thiag0

  I am trying to achieve the following... _4S.NJB_Request request = (from r in db.NJB_Requests where r.RequestId == referenceId select r).Take(1).SingleOrDefault(); Getting the following exception... Message: The null value cannot be assigned to a member with type System.Int32 which is a non-nullable value type. StackTrace: at System.Data.Linq.SqlClient.SqlProvider.Execute(Expression query, QueryInfo queryInfo, IObjectReaderFactory factory, Object[] parentArgs, Object[] userArgs, ICompiledSubQuery[] subQueries, Object lastResult) at System.Data.Linq.SqlClient.SqlProvider.ExecuteAll(Expression query, QueryInfo[] queryInfos, IObjectReaderFactory factory, Object[] userArguments, ICompiledSubQuery[] subQueries) at System.Data.Linq.SqlClient.SqlProvider.System.Data.Linq.Provider.IProvider.Execute(Expression query) at System.Data.Linq.DataQuery`1.System.Linq.IQueryProvider.Execute[S](Expression expression) at System.Linq.Queryable.SingleOrDefault[TSource](IQueryable`1 source) at DAL.SqlDataProvider.MarkNJBPCRequestAsComplete(Int32 referenceId, Int32 processState) I have verified that 'referenceId' does have a value. Anyone know why this would happen in a select statement? Thanks!

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• Linq to SQL and concurrency with Rob Conery repository pattern

  - by David Hall

  I have implemented a DAL using Rob Conery's spin on the repository pattern (from the MVC Storefront project) where I map database objects to domain objects using Linq and use Linq to SQL to actually get the data. This is all working wonderfully giving me the full control over the shape of my domain objects that I want, but I have hit a problem with concurrency that I thought I'd ask about here. I have concurrency working but the solution feels like it might be wrong (just one of those gitchy feelings). The basic pattern is: private MyDataContext _datacontext private Table _tasks; public Repository(MyDataContext datacontext) { _dataContext = datacontext; } public void GetTasks() { _tasks = from t in _dataContext.Tasks; return from t in _tasks select new Domain.Task { Name = t.Name, Id = t.TaskId, Description = t.Description }; } public void SaveTask(Domain.Task task) { Task dbTask = null; // Logic for new tasks omitted... dbTask = (from t in _tasks where t.TaskId == task.Id select t).SingleOrDefault(); dbTask.Description = task.Description, dbTask.Name = task.Name, _dataContext.SubmitChanges(); } So with that implementation I've lost concurrency tracking because of the mapping to the domain task. I get it back by storing the private Table which is my datacontext list of tasks at the time of getting the original task. I then update the tasks from this stored Table and save what I've updated This is working - I get change conflict exceptions raised when there are concurrency violations, just as I want. However, it just screams to me that I've missed a trick. Is there a better way of doing this? I've looked at the .Attach method on the datacontext but that appears to require storing the original version in a similar way to what I'm already doing. I also know that I could avoid all this by doing away with the domain objects and letting the Linq to SQL generated objects all the way up my stack - but I dislike that just as much as I dislike the way I'm handling concurrency.

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• LINQ to Entities exceptions (ElementAtOrDefault and CompareObjectEqual)

  - by OffApps Cory

  I am working on a shipping platform which will eventually automate shipping through several major carriers. I have a ShipmentsView Usercontrol which displayes a list of Shipments (returned by EntityFramework), and when a user clicks on a shipment item, it spawns a ShipmentEditView and passes the ShipmentID (RecordKey) to that view. I initially wrestled with trying to get the context from the parent (ShipmentsView) and finally gave up resolving to get to it later. I wanted to do this to keep a single instance of the context. anyhow, I now create a new instance of the context in my ShipmentEditViewModel, and query against it for the Shipment record. I know I could just pass the record, but I wanted to use the Ocean Framework that Karl Shifflett wrote and don't want to muck about writing new transition methods. So anyhow, I query and when stepping through, I can see that it returns a record, as soon as execution reached the point where it assigned the query result to the e.Result property, it throws up the following exception depending on the query I used. LINQToEntities Dim RecordID As Decimal = CDec(e.Argument) Dim myResult = From ship In _Context.Shipment _ Where ship.ShipID = e.Argument _ Select ship Select Case myResult.Count Case 0 e.Result = New Shipment Case 1 e.Result = myResult(0) Case Else e.Result = Nothing End Select "LINQ to Entities does not recognize the method 'System.Object.CompareObjectEqual(System.Object, System.Object, Boolean)' method, and this method cannot be translated into a store expression. LINQToEntities via Method calls Dim RecordID As Decimal = CDec(e.Argument) Dim myResult = _Context.Shipment.Where(Function(s) s.ShipID = RecordID) Select Case myResult.Count Case 0 e.Result = New Shipment Case 1 e.Result = myResult(0) Case Else e.Result = Nothing End Select LINQ to Entities does not recognize the method 'SnazzyShippingDAL.Shipment ElementAtOrDefault[Shipment] (System.Linq.IQueryable`1[SnazzyShippingDAL.Shipment], Int32)' method, and this method cannot be translated into a store expression. I have been trying to get this thing to display a record for like three days. i am seriously thinking about going back and re=-engineering it without the MVVM pattern (which I realize I am only starting to learn and understand) if only to make the &$^%ed thing work. Any help will be muchly appreciated. Cory

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• LINQ into SortedList

  - by Chris Simmons

  I'm a complete LINQ newbie, so I don't know if my LINQ is incorrect for what I need to do or if my expectations of performance are too high. I've got a SortedList of objects, keyed by int; SortedList as opposed to SortedDictionary because I'll be populating the collection with pre-sorted data. My task is to find either the exact key or, if there is no exact key, the one with the next higher value. If the search is too high for the list (e.g. highest key is 100, but search for 105), return null. // The structure of this class is unimportant. Just using // it as an illustration. public class CX { public int KEY; public DateTime DT; } static CX getItem(int i, SortedList<int, CX> list) { var items = (from kv in list where kv.Key >= i select kv.Key); if (items.Any()) { return list[items.Min()]; } return null; } Given a list of 50,000 records, calling getItem 500 times takes about a second and a half. Calling it 50,000 times takes over 2 minutes. This performance seems very poor. Is my LINQ bad? Am I expecting too much? Should I be rolling my own binary search function?

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• LINQ-to-SQL: Could not find key member 'x' of key 'x' on type 'y'

  - by Austin Hyde

  I am trying to connect my application to a SQLite database with LINQ-to-SQL, and so far everything has worked fine. The only hitch was that the SQLite provider I am using does not support code generation (unless I was doing something wrong), so I manually coded the 4 tables in the DB. The solution builds properly, but will not run, giving me the error message Could not find key member 'ItemType_Id' of key 'ItemType_Id' on type 'Item'. The key may be wrong or the field or property on 'Item' has changed names. I have checked and double checked spellings and field names on the database and in the attribute mappings, but could not find any problems. The SQL for the table looks like this: CREATE TABLE [Items] ( [Id] integer PRIMARY KEY AUTOINCREMENT NOT NULL, [Name] text NOT NULL, [ItemType_Id] integer NOT NULL ); And my mapping code: [Table(Name="Items")] class Item { // [snip] [Column(Name = "Id", IsPrimaryKey=true, IsDbGenerated=true)] public int Id { get; set; } // [snip] [Column(Name="ItemType_Id")] public int ItemTypeId { get; set; } [Association(Storage = "_itemType", ThisKey = "ItemType_Id")] public ItemType ItemType { get { return _itemType.Entity; } set { _itemType.Entity = value; } } private EntityRef<ItemType> _itemType; // [snip] } This is really my first excursion into LINQ-to-SQL, and am learning as I go, but I cannot seem to get past this seeming simple problem. Why cannot LINQ see my association?

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• extracting RDL data using LINQ

  - by BobC

  I'm working with some SQL Report definition files (RDLs), using LINQ to extract component query statements for validation. I'm trying to extract the <DataSet> elements from under the <DataSets> element. I seem to be getting hung up with one of the elements under <DataSet><Fields><Field> which has a namespace qualifier <rd:TypeName> I've been using LINQ to XML for other parts of the files where there is no namespace qualifiers with no trouble, by specifying a default namespace. The RDL specifies two namespaces: xmlns="http://schemas.microsoft.com/sqlserver/reporting/2005/01/reportdefinition" xmlns:rd="http://schemas.microsoft.com/SQLServer/reporting/reportdesigner"> When I try to get the <DataSets> element, however, I get the following error: System.Xml.XmlException - The ':' character, hexadecimal value 0x3A, cannot be included in a name. I know it has to do with the namespace qualifier (rd:) in one of the child elements, but I'm having difficulty getting a LINQ expression that works. Any help would be appreciated. Thanks!

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• VS2010 / Target Framework = 3.5 / Building on Continuous Integration Server

  - by granadaCoder

  I'm checking into upgrading to VS2010. Our production servers only have 3.5 Framework and it will be 6-9 months before they are updated. We also have a Continuous Integration Server, running CruiseControl.NET (CC.NET). It has the 3.5 Framework on it as well. Our implementation of CC.NET mainly calls msbuild.exe MySolution.msbuild. (We encapsulate most of the build logic into .msbuild files fyi) Inside the .msbuild file, the following is the "Build" syntax: < Target Name="Build" DependsOnTargets="Checkout" < MSBuild Projects="$(WorkingCheckout)\MySolution.sln" Targets="Build" Properties="Configuration=$(Configuration)" < Output TaskParameter="TargetOutputs" ItemName="TargetOutputsItemName"< /Output < /MSBuild < /Target (A few spaces added to make it display here) =========== I know the VS2010 can "Target" the 3.5 Framework. My question is what happens when I have a VS2010 dev machine, and I check the VS2010 .sln and .csproj(s) files into source control (svn, btw).....will the CC.NET machine ~~which only have the 3.5 Framework installed on it........be able to build the .sln ? I guess I could test it, but the catch22 is that I don't have VS2010 (yet). So I'm asking before I try (the trial or a real install. ............. Any ideas what will happen? I guess the crux question is, what will happen. c:\WINDOWS\Microsoft.NET\Framework\v3.5\MSBuild.exe "MyVS2010SolutionFile.sln" ?? My hopeful goal would be, allow the developers to have VS2010 (now!), and it still be "ok" for the CC.NET machine and the Production Servers which will only have the 3.5 Framework on them for the foreseeable future. Just to be clear, developers NEVER create deployable builds. Only the CC.NET machine produces builds that will be pushed as production builds. Any help?

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• Linq: the linked objects are null, why?

  - by user46503

  Hello, I have several linked tables (entities). I'm trying to get the entities using the following linq: ObjectQuery<Location> locations = context.Location; ObjectQuery<ProductPrice> productPrice = context.ProductPrice; ObjectQuery<Product> products = context.Product; IQueryable<ProductPrice> res1 = from pp in productPrice join loc in locations on pp.Location equals loc join prod in products on pp.Product equals prod where prod.Title.ToLower().IndexOf(Word.ToLower()) > -1 select pp; This query returns 2 records, ProductPrice objects that have linked object Location and Product but they are null and I cannot understand why. If I try to fill them in the linq as below: res = from pp in productPrice join loc in locations on pp.Location equals loc join prod in products on pp.Product equals prod where prod.Title.ToLower().IndexOf(Word.ToLower()) > -1 select new ProductPrice { ProductPriceId = pp.ProductPriceId, Product = prod }; I have the exception "The entity or complex type 'PBExplorerData.ProductPrice' cannot be constructed in a LINQ to Entities query" Could someone please explain me what happens and what I need to do? Thanks

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• C# LINQ to XML missing space character.

  - by Fossaw

  I write an XML file "by hand", (i.e. not with LINQ to XML), which sometimes includes an open/close tag containing a single space character. Upon viewing the resulting file, all appears correct, example below... <Item> <ItemNumber>3</ItemNumber> <English> </English> <Translation>Ignore this one. Do not remove.</Translation> </Item> ... the reasons for doing this are various and irrelevent, it is done. Later, I use a C# program with LINQ to XML to read the file back and extract the record... XElement X_EnglishE = null; // This is CRAZY foreach (XElement i in Records) { X_EnglishE = i.Element("English"); // There is only one damned record! } string X_English = X_EnglishE.ToString(); ... and test to make sure it is unchanged from the database record. I detect a change, when processing Items where the field had the single space character... +E+ Text[3] English source has been altered: Was: >>> <<< Now: >>><<< ... the and <<< parts I added to see what was happening, (hard to see space characters). I have fiddled around with this but can't see why this is so. It is not absolutely critical, as the field is not used, (yet), but I cannot trust C# or LINQ or whatever is doing this, if I do not understand why it is so. So what is doing that and why?

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• Trouble with LINQ databind to GridView and RowDataBound

  - by Michael

  Greetings all, I am working on redesigning my personal Web site using VS 2008 and have chosen to use LINQ to create by data-access layer. Part of my site will be a little app to help manage my budget better. My first LINQ query does successfully execute and display in a GridView, but when I try to use a RowDataBound event to work with the results and refine them a bit, I get the error: The type or namespace name 'var' could not be found (are you missing a using directive or an assembly reference?) This interesting part is, if I just try to put in a var s = "s"; anywhere else in the same file, I get the same error too. If I go to other files in the web project, var s = "s"; compiles fine. Here is the LINQ Query call: public static IQueryable pubGetRecentTransactions(int param_accountid) { clsDataContext db; db = new clsDataContext(); var query = from d in db.tblMoneyTransactions join p in db.tblMoneyTransactions on d.iParentTransID equals p.iTransID into dp from p in dp.DefaultIfEmpty() where d.iAccountID == param_accountid orderby d.dtTransDate descending, d.iTransID ascending select new { d.iTransID, d.dtTransDate, sTransDesc = p != null ? p.sTransDesc : d.sTransDesc, d.sTransMemo, d.mTransAmt, d.iCheckNum, d.iParentTransID, d.iReconciled, d.bIsTransfer }; return query; } protected void Page_Load(object sender, EventArgs e) { if (!this.IsPostBack) { this.prvLoadData(); } } internal void prvLoadData() { prvCtlGridTransactions.DataSource = clsMoneyTransactions.pubGetRecentTransactions(2); prvCtlGridTransactions.DataBind(); } protected void prvCtlGridTransactions_RowDataBound(object sender, GridViewRowEventArgs e) { if (e.Row.RowType == DataControlRowType.DataRow) { var datarow = e.Row.DataItem; var s = "s"; e.Row.Cells[0].Text = datarow.dtTransDate.ToShortDateString(); e.Row.Cells[1].Text = datarow.sTransDesc; e.Row.Cells[2].Text = datarow.mTransAmt.ToString("c"); e.Row.Cells[3].Text = datarow.iReconciled.ToString(); }//end if }//end RowDataBound My googling to date hasn't found a good answer, so I turn it over to this trusted community. I appreciate your time in assisting me.

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• C# LINQ to XML nissing space character.

  - by Fossaw

  I write an XML file "by hand", (i.e. not with LINQ to XML), which sometimes includes an open/close tag containing a single space character. Upon viewing the resulting file, all appears correct, example below... <Item> <ItemNumber>3</ItemNumber> <English> </English> <Translation>Ignore this one. Do not remove.</Translation> </Item> ... the reasons for doing this are various and irrelevent, it is done. Later, I use a C# program with LINQ to XML to read the file back and extract the record... XElement X_EnglishE = null; // This is CRAZY foreach (XElement i in Records) { X_EnglishE = i.Element("English"); // There is only one damned record! } string X_English = X_EnglishE.ToString(); ... and test to make sure it is unchanged from the database record. I detect a change, when processing Items where the field had the single space character... +E+ Text[3] English source has been altered: Was: >>> <<< Now: >>><<< ... the and <<< parts I added to see what was happening, (hard to see space characters). I have fiddled around with this but can't see why this is so. It is not absolutely critical, as the field is not used, (yet), but I cannot trust C# or LINQ or whatever is doing this, if I do not understand why it is so. So what is doing that and why?

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• LINQ to XML contents of child records.

  - by Fossaw

  I have this LINQ to XML enquiry... var Records = from Item in XDoc.Root.Elements("Item") where (string)Item.Element("ItemNumber") == item.ID.ToString select Item; ... where ItemNumber is a reference number used in the XML, (originally written by this program but manually edited by "others"), and item.ID is the database version of the same thing. The query executes, and I can test for the number of entries in the result fine... if (Records.Count() < 1) ... you get the idea. I have established that there is only one record. Each Item has several child fields. I want to test the values of the child fields are reasonable before passing them on to the database update sub-system. The XML is produced by the program, but edited by users, so I need to really check what is coming back. So I tried... if (DB_English.ToString() != Records.Elements("English").ToString()) ... DB_English is from the database, but the XML in Records, does not contain the contents of that field, it contains... System.Xml.Linq.Extensions+<GetElements>d__29`1[System.Xml.Linq.XElement] ... so, how do I get the value of this element in the XML file? I need to check the field in the XML has not been altered, (the manual editors of this data file are not potentially 100% reliable).

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• Update mapping table in Linq

  - by Gary McGill

  I have a table Customers with a CustomerId field, and a table of Publications with a PublicationId field. Finally, I have a mapping table CustomersPublications that records which publications a customer can access - it has two fields: CustomerId field PublicationId. For a given customer, I want to update the CustomersPublications table based on a list of publication ids. I want to remove records in CustomersPublications where the PublicationId is not in the list, and add new records where the PublicationId is in the list but not already in the table. This would be easy in SQL, but I can't figure out how to do it in Linq. For the delete part, I tried: var recordsToDelete = dataContext.CustomersPublications.Where ( cp => (cp.CustomerId == customerId) && ! publicationIds.Contains(cp.PublicationId) ); dataContext.CustomersPublications.DeleteAllOnSubmit(recordsToDelete); ... but that didn't work. I got an error: System.NotSupportedException: Method 'Boolean Contains(Int32)' has no supported translation to SQL So, I tried using Any(), as follows: var recordsToDelete = dataContext.CustomersPublications.Where ( cp => (cp.CustomerId == customerId) && ! publicationIds.Any(p => p == cp.PublicationId) ); ... and this just gives me another error: System.NotSupportedException: Local sequence cannot be used in LINQ to SQL implementation of query operators except the Contains() operator Any pointers? [I have to say, I find Linq baffling (and frustrating) for all but the simplest queries. Better error messages would help!]

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• Need advice on comparing the performance of 2 equivalent linq to sql queries

  - by uvita

  I am working on tool to optimize linq to sql queries. Basically it intercepts the linq execution pipeline and makes some optimizations like for example removing a redundant join from a query. Of course, there is an overhead in the execution time before the query gets executed in the dbms, but then, the query should be processed faster. I don't want to use a sql profiler because I know that the generated query will be perform better in the dbms than the original one, I am looking for a correct way of measuring the global time between the creation of the query in linq and the end of its execution. Currently, I am using the Stopwatch class and my code looks something like this: var sw = new Stopwatch(); sw.Start(); const int amount = 100; for (var i = 0; i < amount; i++) { ExecuteNonOptimizedQuery(); } sw.Stop(); Console.Writeline("Executing the query {2} times took: {0}ms. On average, each query took: {1}ms", sw.ElapsedMilliseconds, sw.ElapsedMilliseconds / amount, amount); Basically the ExecutenNonOptimizedQuery() method creates a new DataContext, creates a query and then iterates over the results. I did this for both versions of the query, the normal one and the optimized one. I took the idea from this post from Frans Bouma. Is there any other approach/considerations I should take? Thanks in advance!

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• oData/ADO.NET Data Services using LINQ-to-SQL with a decryption layer

  - by Program.X

  I have written an application using LINQ-to-SQL that submits a web form into a database. I absact the LINQ-to-SQL away using a Repository pattern. This repository has the basic methods: Get(), Save(), etc. As a development of the project, I needed to encrypt certain fields in the form. This was trivial, as I just added the encryption calls to the Get(), Save() methods in the Repository. Now, I want to put an oData layer over it, to allow RESTful extraction from MS Excel 2010 (when it comes out). I have this working, after a few stumbles on useless error messages, etc. However, obviously, those encrypted fields are still encrypted. My repository pattern would have decrypted these for me. As far as I know, I have to directly bind my oData service to the LINQ-to-SQL context for the schema, etc. to work - unless I enter a whole world of pain (any URLs appreciated). Is there a way I can insert my encryption/decryption layer into the request so decryption is done "on the fly"? I looked at the OnStartProcessingRequest() overload of DataService but this doesn't seem that useful.

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• Acceessing some aggregate functions in a linq datasource in a GridView

  - by Stephen Pellicer

  I am working on a traditional WebForms project. In the project I am trying out some Linq datasources with plans to eventually migrate to an MVC architecture. I am still very new to Linq. I have a GridView using a Linq datasource. The entities I am showing has a to many relationship and I would like to get the maximum value of a column in the many side of the relationship. I can show properties of the base entity in the gridview: <asp:TemplateField HeaderText="Number" SortExpression="tJobBase.tJob.JobNumber"> <ItemTemplate> <asp:Label ID="Label1" runat="server" Text='<%# Bind("tJobBase.tJob.JobNumber") %>'> </asp:Label> </ItemTemplate> </asp:TemplateField> I can also show the count of the many related property: <asp:TemplateField HeaderText="Number" SortExpression="tJobBase.tJob.tHourlies.Count"> <ItemTemplate> <asp:Label ID="Label1" runat="server" Text='<%# Bind("tJobBase.tJob.tHourlies.Count") %>'> </asp:Label> </ItemTemplate> </asp:TemplateField> Is there a way to get the max value of a column called WeekEnding in the tHourlies collection to show in the GridView?

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• "Order By" in LINQ-to-SQL Causes performance issues

  - by panamack

  I've set out to write a method in my C# application which can return an ordered subset of names from a table containing about 2000 names starting at the 100th name and returning the next 20 names. I'm doing this so I can populate a WPF DataGrid in my UI and do some custom paging. I've been using LINQ to SQL but hit a snag with this long executing query so I'm examining the SQL the LINQ query is using (Query B below). Query A runs well: SELECT TOP (20) [t0].[subject_id] AS [Subject_id], [t0].[session_id] AS [Session_id], [t0].[name] AS [Name] FROM [Subjects] AS [t0] WHERE (NOT (EXISTS( SELECT NULL AS [EMPTY] FROM ( SELECT TOP (100) [t1].[subject_id] FROM [Subjects] AS [t1] WHERE [t1].[session_id] = 1 ORDER BY [t1].[name] ) AS [t2] WHERE [t0].[subject_id] = [t2].[subject_id] ))) AND ([t0].[session_id] = 1) Query B takes 40 seconds: SELECT TOP (20) [t0].[subject_id] AS [Subject_id], [t0].[session_id] AS [Session_id], [t0].[name] AS [Name] FROM [Subjects] AS [t0] WHERE (NOT (EXISTS( SELECT NULL AS [EMPTY] FROM ( SELECT TOP (100) [t1].[subject_id] FROM [Subjects] AS [t1] WHERE [t1].[session_id] = 1 ORDER BY [t1].[name] ) AS [t2] WHERE [t0].[subject_id] = [t2].[subject_id] ))) AND ([t0].[session_id] = 1) ORDER BY [t0].[name] When I add the ORDER BY [t0].[name] to the outer query it slows down the query. How can I improve the second query? This was my LINQ stuff Nick int sessionId = 1; int start = 100; int count = 20; // Query subjects with the shoot's session id var subjects = cldb.Subjects.Where<Subject>(s => s.Session_id == sessionId); // Filter as per params var orderedSubjects = subjects .OrderBy<Subject, string>( s => s.Col_zero ); var filteredSubjects = orderedSubjects .Skip<Subject>(start) .Take<Subject>(count);

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• Call method immediately after object construction in LINQ query

  - by Steffen

  I've got some objects which implement this interface: public interface IRow { void Fill(DataRow dr); } Usually when I select something out of db, I go: public IEnumerable<IRow> SelectSomeRows { DataTable table = GetTableFromDatabase(); foreach (DataRow dr in table.Rows) { IRow row = new MySQLRow(); // Disregard the MySQLRow type, it's not important row.Fill(dr); yield return row; } } Now with .Net 4, I'd like to use AsParallel, and thus LINQ. I've done some testing on it, and it speeds up things alot (IRow.Fill uses Reflection, so it's hard on the CPU) Anyway my problem is, how do I go about creating a LINQ query, which calls Fills as part of the query, so it's properly parallelized? For testing performance I created a constructor which took the DataRow as argument, however I'd really love to avoid this if somehow possible. With the constructor in place, it's obviously simple enough: public IEnumerable<IRow> SelectSomeRowsParallel { DataTable table = GetTableFromDatabase(); return from DataRow dr in table.Rows.AsParallel() select new MySQLRow(dr); } However like I said, I'd really love to be able to just stuff my Fill method into the LINQ query, and thus not need the constructor overload.

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• Linq to SQL code generator features

  - by Anders Abel

  I'm very fond of Linq to SQL and the programming model it encourages. I think that in many cases when you are in control of both the database schema and the code it is not worth the effort to have different relational and object models for the data. Working with Linq to SQL makes it simple to have type safe data access from .NET, using the partial extension methods to implement business rules. Unfortunately I do not like the dbml designer due to the lack of a schema refresh function. So far I have used SqlMetal, but that lacks the customization options of the dbml designer. Because of that I've started working on a tool which regenerates the whole code file like SqlMetal, but has the ability to do the customizations that are available in the dbml designer (and maybe more in the future). The customizations will be described in an xml file which only contains those parts that shouldn't have default values. This should keep the xml file size down as well as the maintenance burden of it. To help me focus on the right features, I would like to know: What would be your favourite feature in a linq to sql code generator?

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• using linq to sql

  - by mazhar

  Well I am new to this orm stuff. We have to create a large project . I read about linq to sql . will it be appropiate to use it in the project of high risk . i found no problem with it personally but the thing is that there will be no going back once started.So i need some feedback from the orm gurus here at the msdn.Will entity framework will be better?( I am in doubt about link to sql because I have read and heard negative feedback here and there) I will be using mvc2 as the framework. So please give the feedback about linq to sql in this regard. q2) Also I am a fan of stored procedure as they are precomputed and fasten up the thing and I have never worked without them.I know that linq to sql support stored procedures but will it be feasible to give up stored procedure seeing the beautiful data access layer generated with little effort as we are also in a need of rapid development. q3) If some changes to some fields required in the database in Link to Sql how will the changes be accommodated in the data access layer.

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• using linq to sql

  - by user324831

  Well I am new to this orm stuff. We have to create a large project . I read about linq to sql . will it be appropiate to use it in the project of high risk . i found no problem with it personally but the thing is that there will be no going back once started.So i need some feedback from the orm gurus here at the msdn.Will entity framework will be better?( I am in doubt about link to sql because I have read and heard negative feedback here and there) I will be using mvc2 as the framework. So please give the feedback about linq to sql in this regard. q2) Also I am a fan of stored procedure as they are precomputed and fasten up the thing and I have never worked without them.I know that linq to sql support stored procedures but will it be feasible to give up stored procedure seeing the beautiful data access layer generated with little effort as we are also in a need of rapid development. q3) If some changes to some fields required in the database in Link to Sql how will the changes be accommodated in the data access layer.

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