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  • How to Link VS2010 Database Project and LINQ to SQL

    - by Jason
    As I am working with the new database projects in VS2010, and as I am learning LINQ to SQL, I am curious as to the best way to link the two groups of information so that when I update one, the other updates along with it. From my research here at SO, as well as in Google, it appears the general rule of thumb is: "Build the database, and then create your LINQ to SQL classes." Of course, if I make a change in my database, the LINQ to SQL doesn't update automatically and I have to do it by hand. This is fairly simple right now as my database is small, but I am curious if there is an easier way for this to happen. In addition, the LINQ to SQL tool is pretty nice. The ability to create tables, add associations, and even create inheritance is very simple. As my second question, I am curious as to whether or not VS2010 can work the other way - I design the database in the DBLM file and then link it back to my database project. I appreciate any help with either of these two questions. I'm really interested in making this as easy as possible to reduce errors during development and improve the speed at which changes can be made.

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  • Selecting a multi-dimensional array in LINQ

    - by mckhendry
    I have a task where I need to translate a DataTable to a two-dimensional array. That's easy enough to do by just looping over the rows and columns (see example below). private static string[,] ToArray(DataTable table) { var array = new string[table.Rows.Count,table.Columns.Count]; for (int i = 0; i < table.Rows.Count; ++i) for (int j = 0; j < table.Columns.Count; ++j) array[i, j] = table.Rows[i][j].ToString(); return array; } What I'd really like to do is use a select statement in LINQ to generate that 2D array. Unfortunately it looks like there is no way in LINQ to select a multidimensional array. Yes, I'm aware that I can use LINQ to select a jagged array, but that's not what I want. Is my assumption correct, or is there a way to use LINQ to select a multi-dimensional array?

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  • Merging sequences by type With LINQ

    - by jankor
    I want to use LINQ to convert this IEnumerable<int>[] value1ByType = new IEnumerable<int>[3]; value1ByType[0]= new [] { 0}; value1ByType[1]= new [] {10,11}; value1ByType[2]= new [] {20}; var value2ToType = new Dictionary<int,int> { {100,0}, {101,1}, {102,2}, {103,1}}; to this var value2ToValue1 = new Dictionary<int,int> { {100, 0}, {101,10}, {102,20}, {103,11}}; Is there a way to do this with LINQ? Without LINQ I would use multiple IEnumerators, one for each IEnumerable of value1ByType. like this: // create enumerators var value1TypeEnumerators = new List<IEnumerator<int>>(); for (int i = 0; i < value1ByType.Length; i++) { value1TypeEnumerators.Add(value1ByType[i].GetEnumerator()); value1TypeEnumerators[i].MoveNext(); } // create wanted dictionary var value2ToValue1 = new Dictionary<int, int>(); foreach (var item in Value2ToType) { int value1=value1TypeEnumerators[item.Value].Current; value2ToValue1.Add(item.Key, value1); value1TypeEnumerators[item.Value].MoveNext(); } Any Idea how to do this in LINQ?

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  • LINQ Query please help C#.Net.

    - by Paul Matthews
    I'm very new to LINQ and struggling to find the answers. I have a simple SQL query. Select ID, COUNT(ID) as Selections, OptionName, SUM(Units) as Units FROM tbl_Results GROUP BY ID, OptionName. The results I got were: '1' '4' 'Approved' '40' '2' '1' 'Rejected' '19' '3' '2' 'Not Decided' '12' Due to having to encrypt all my data in the database I'm unable to do sums. Therefore I have now brought back the data and decrypt it in the application layer. Results would be: '1' 'Approved' '10' '3' 'Not Deceided' '6' '2' 'Rejected' '19' '1' 'Approved' '15' '1' 'Approved' '5' '3' 'Not Deceided' '6' '1' 'Approved' '10' using a simple class I have called back the above results, and put them in a list class. public class results { public int ID {get;set;} public string OptionName {get;set;} public int Unit {get;set;} } I almost have the LINQ query to bring back the results like the SQL query at the top var q = from r in Results group p.Unit by p.ID int g select new {ID = g.Key, Selections = g.Count(), Units = g.Sum()}; How do I ensure my LINQ query also give me the Option Name? Also if I created a class called Statistics to hold my results how would I modify the LINQ query to give me list result set? public class results { public int ID {get;set;} public int NumberOfSelections { get; set; } public string OptionName {get;set;} public int UnitTotal {get;set;} }

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  • Show me your Linq to SQL architectures!

    - by Brad Heller
    I've been using Linq to SQL for a new implementation that I've been working on. I have about 5000 lines of code and am a little ways from a solid demo. I've been pretty satisfied with Linq to SQL so far -- the tools are excellent and pretty painless and it allows you to get a DAL up and running quickly. That said, there are some major draw backs that I just keep hitting over and over again. Namely how to handle separation of concerns between my DAL and my business layer and juggling that with different data contexts. Here is the architecture I've been using: My repositories do all my data access and they return Linq to SQL objects. Each of my Linq to SQL objects implements an IDetachable interface. A typical implementation looks like this: partial class PaymentDetail : IDetachable { #region IDetachable Members public bool IsAttached { get { return PropertyChanging != null; } } public void Detach() { if (IsAttached) { PropertyChanged = null; PropertyChanging = null; Transaction.Detach(); } } #endregion } Every time I do a DAL operation in my repository I "detach" when I'm done with the object (and it should theoretically detach from any child objects) to remove the DataContext's context. Like I said, this works pretty well, but there are some edge cases that seem to be a big pain in the ass. For instance, my Transaction object has many PaymentDetails. Even when there are no PaymentDetails in that collection it's still attached to the DataContext's context! Thus, if I try to update (I update by Attach()ing to the object and then SubmitChanges()) I get that dreaded "An attempt has been made to Attach or Add an entity that is not new, perhaps having been loaded from another DataContext. This is not supported." message. Anyway, I'm starting to doubt that this technology was a good gamble. Has anyone got a decent architecture that they're willing to share? I'd really love to use this technology but I feel like I spend 1/3 of my time just debugging is retarded quirks!

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  • VB.NET switching from ADO.NET to LINQ

    - by Cj Anderson
    I'm VERY new to Linq. I have an application I wrote that is in VB.NET 2.0. Works great, but I'd like to switch this application to Linq. I use ADO.NET to load XML into a datatable. The XML file has about 90,000 records in it. I then use the Datatable.Select to perform searches against that Datatable. The search control is a free form textbox. So if the user types in terms it searches instantly. Any further terms that are typed in continue to restrict the results. So you can type in Bob, or type in Bob Barker. Or type in Bob Barker Price is Right. The more criteria typed in the more narrowed your result. I bind the results to a gridview. Moving forward what all do I need to do? From a high level, I assume I need to: 1) Go to Project Properties -- Advanced Compiler Settings and change the Target framework to 3.5 from 2.0. 2) Add the reference to System.XML.Linq, Add the Imports statement to the classes. So I'm not sure what the best approach is going forward after that. I assume I use XDocument.Load, then my search subroutine runs against the XDocument. Do I just do the standard Linq query for this sort of repeated search? Like so: var people = from phonebook in doc.Root.Elements("phonebook") where phonebook.Element("userid") = "whatever" select phonebook; Any tips on how to best implement?

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  • Alternatives to LINQ To SQL on high loaded pages

    - by Alex
    To begin with, I LOVE LINQ TO SQL. It's so much easier to use than direct querying. But, there's one great problem: it doesn't work well on high loaded requests. I have some actions in my ASP.NET MVC project, that are called hundreds times every minute. I used to have LINQ to SQL there, but since the amount of requests is gigantic, LINQ TO SQL almost always returned "Row not found or changed" or "X of X updates failed". And it's understandable. For instance, I have to increase some value by one with every request. var stat = DB.Stats.First(); stat.Visits++; // .... DB.SubmitChanges(); But while ASP.NET was working on those //... instructions, the stats.Visits value stored in the table got changed. I found a solution, I created a stored procedure UPDATE Stats SET Visits=Visits+1 It works well. Unfortunately now I'm getting more and more moments like that. And it sucks to create stored procedures for all cases. So my question is, how to solve this problem? Are there any alternatives that can work here? I hear that Stackoverflow works with LINQ to SQL. And it's more loaded than my site.

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  • LINQ Joins - Performance

    - by Meiscooldude
    I am curious on how exactly LINQ (not LINQ to SQL) is performing is joins behind the scenes in relation to how Sql Server performs joins. Sql Server before executing a query, generates an Execution Plan. The Execution Plan is basically an Expression Tree on what it believes is the best way to execute the query. Each node provides information on whether to do a Sort, Scan, Select, Join, ect. On a 'Join' node in our execution plan, we can see three possible algorithms; Hash Join, Merge Join, and Nested Loops Join. Sql Server will choose which algorithm to for each Join operation based on expected number of rows in Inner and Outer tables, what type of join we are doing (some algorithms don't support all types of joins), whether we need data ordered, and probably many other factors. Join Algorithms: Nested Loop Join: Best for small inputs, can be optimized with ordered inner table. Merge Join: Best for medium to large inputs sorted inputs, or an output that needs to be ordered. Hash Join: Best for medium to large inputs, can be parallelized to scale linearly. LINQ Query: DataTable firstTable, secondTable; ... var rows = from firstRow in firstTable.AsEnumerable () join secondRow in secondTable.AsEnumerable () on firstRow.Field<object> (randomObject.Property) equals secondRow.Field<object> (randomObject.Property) select new {firstRow, secondRow}; SQL Query: SELECT * FROM firstTable fT INNER JOIN secondTable sT ON fT.Property = sT.Property Sql Server might use a Nested Loop Join if it knows there are a small number of rows from each table, a merge join if it knows one of the tables has an index, and Hash join if it knows there are a lot of rows on either table and neither has an index. Does Linq choose its algorithm for joins? or does it always use one?

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  • Problem with LINQ query

    - by Niels Bosma
    The following works fine: (from e in db.EnquiryAreas from w in db.WorkTypes where w.HumanId != null && w.SeoPriority > 0 && e.HumanId != null && e.SeoPriority > 0 && db.Enquiries.Where(f => f.WhereId == e.Id && f.WhatId == w.Id && f.EnquiryPublished != null && f.StatusId != EnquiryMethods.STATUS_INACTIVE && f.StatusId != EnquiryMethods.STATUS_REMOVED && f.StatusId != EnquiryMethods.STATUS_REJECTED && f.StatusId != EnquiryMethods.STATUS_ATTEND ).Any() select new { EnquiryArea = e, WorkType = w }); But: (from e in db.EnquiryAreas from w in db.WorkTypes where w.HumanId != null && w.SeoPriority > 0 && e.HumanId != null && e.SeoPriority > 0 && EnquiryMethods.BlockOnSite(db.Enquiries.Where(f => f.WhereId == e.Id && f.WhatId == w.Id)).Any() select new { EnquiryArea = e, WorkType = w }); + public static IQueryable<Enquiry> BlockOnSite(IQueryable<Enquiry> linq) { return linq.Where(e => e.EnquiryPublished != null && e.StatusId != STATUS_INACTIVE && e.StatusId != STATUS_REMOVED && e.StatusId != STATUS_REJECTED && e.StatusId != STATUS_ATTEND ); } I get the following error: base {System.SystemException}: {"Method 'System.Linq.IQueryable1[X.Enquiry] BlockOnSite(System.Linq.IQueryable1[X.Enquiry])' has no supported translation to SQL."}

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  • Advice on Linq to SQL mapping object design

    - by fearofawhackplanet
    I hope the title and following text are clear, I'm not very familiar with the correct terms so please correct me if I get anything wrong. I'm using Linq ORM for the first time and am wondering how to address the following. Say I have two DB tables: User ---- Id Name Phone ----- Id UserId Model The Linq code generator produces a bunch of entity classes. I then write my own classes and interfaces which wrap these Linq classes: class DatabaseUser : IUser { public DatabaseUser(User user) { _user = user; } public Guid Id { get { return _user.Id; } } ... etc } so far so good. Now it's easy enough to find a users phones from Phones.Where(p => p.User = user) but surely comsumers of the API shouldn't need to be writing their own Linq queries to get at data, so I should wrap this query in a function or property somewhere. So the question is, in this example, would you add a Phones property to IUser or not? In other words, should my interface specifically be modelling my database objects (in which case Phones doesn't belong in IUser), or are they actually simply providing a set of functions and properties which are conceptually associated with a User (in which case it does)? There seems drawbacks to both views, but I'm wondering if there is a standard approach to the problem. Or just any general words of wisdom you could share. My first thought was to use extension methods but in fact that doesn't work in this case.

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  • L2E many to many query

    - by 5YrsLaterDBA
    I have four tables: Users PrivilegeGroups rdPrivileges LinkPrivilege ----------- ---------------- --------------- --------------- userId(pk) privilegeGroupId(pk) privilegeId(pk) privilegeId(pk, fk) privilegeGroupId(fk) name code privilegeGroupId(pk, fk) L2E will not create LinkPrivilege entity for me. So we only have Users, PrivilegeGroups and rdPrivileges entities. PrivilegeGroups and rdPrivileges are many to many relationship. What I need to do is retrieve all code from rdPrivileges table based on a passed in userId. How can I do it? EDIT working code: var acc = from u in db.Users from pg in db.PrivilegeGroups from p in pg.rdPrivileges where u.UserId == userId && u.PrivilegeGroups.PrivilegeGroupId == pg.PrivilegeGroupId select p.Code;

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  • LINQ entity query performance

    - by Abdel Olakara
    Hi all, I have a silly question. I would like to know if there is performance deference in these two quries: var cObject = from cust in entities.Customer where cust.id == cid select cust; and var cObject = entities.Customer.First( c=> c.id == cid); My query return only one record as I am querying with the primary key. But do they make any difference?

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  • Linq to Entity Dynamic where clause

    - by GodSmart
    I have Linq to Entity query like you can see below I am using it five times in my code, everything that change is where clause. is it possible to create a method and pass just where values, not to write all code five times. Thank you items = from t1 in _entities.table1 join t2 in _entities.Table2 on t1.column1 equals t2.column1 join t3 in _entities.Table3 on t1.column2 equals t3.column2 join t4 in _entities.Table4 on t1.column3 equals t4.column3 where **t1.column5 == Something** select new { t1.column7, t2.column8, t3.column9, t4.column10 };

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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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  • Entity Framework: How to bind related products

    - by Waheed
    I am using the following Linq query from p in Product.Include("ProductDetails.Colors") where p.ProductID.Equals(18) select p; And then using the result of this query to bind the GridView. The productDetails are bind to the grid fine, but the Colors are not bind. To bind colors i am using <%# Eval("Colors.CategoryName") %. Error is " Field or property with the name 'Colors.CategoryName' was not found on the selected data source." But in a loop i am getting this fine. foreach (ProductDetails proDet in pd.ProductDetails) { string bar = proDet.BarCode; string color = proDet.Colors.CategoryName; }

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  • C# LINQ Oracle date Functions

    - by user1079925
    I am trying to generate a sql statement to be used in Oracle11g, using linq. The problem arises when using dates: The SQL generated by linq gives SELECT * FROM <table> WHERE start_date > '24/11/2012 00:00:00' and end_date < '28/11/2012 00:00:00' This causes an oracle error: ORA-01830 - date format picture ends before converting entire input string Adding TO_DATE to the query fixes the ORA-01830, as it is converting the string to a oracle date whilst now knowing the date format. SELECT * FROM <table> WHERE start_date > TO_DATE('24/11/2012 00:00:00','DD/MM/YYYY HH24:MI:SS') and end_date < TO_DATE('28/11/2012 00:00:00','DD/MM/YYYY HH24:MI:SS') So, is there a way to add TO_DATE to LINQ (for oracle)? If not, please tell me how to work around this issue. Thanks

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  • What is the leading LINQ for JavaScript library?

    - by Tom Tresansky
    I'm looking for a JavaScript library that will allow me to query complex JSON objects using a LINQ-like syntax. A quick search found a couple of promising options that look they might offer what I need: LINQ to JavaScript and jLinq Does any one have any experience using them? What are some pros and cons? Is the performance comparable? Does the function-passing syntax of LINQ to JavaScript offer any hidden benefits (I personally find the syntax of jLinq more appealing on first glance)? What have you found lacking in either project? Did you ever try contacting the authors? How responsive were they? What project is more widely used?

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  • LLBLGEN: Linq to LLBGEN don't work

    - by StreamT
    I want to make custom select from the database table using Linq. We use LLBGEN as ORM solution. I can't do LINQ query to Entities Collection Class unless I call GetMulti(null) method of it. Is it possible to do LINQ query to LLBGEN without extracting all table first? BatchCollection batches = new BatchCollection(); BatchEntity batch = batches.AsQueryable() .Where(i => i.RegisterID == 3) .FirstOrDefault(); // Exception: Sequence don't contains any elements batches = new BatchCollection(); batches.GetMulti(null); // I don't want to extract the whole table. BatchEntity batch = batches.AsQueryable() .Where(i => i.RegisterID == 3) .FirstOrDefault(); //Works fine

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  • Teaching coworkers LINQ...

    - by cyberzed
    I have set myself upon a journey to educate my coworkers (all have accepted my mission, even the boss). Every day I seem to find a piece of code that could have been less error prone if my coworkers knew more about the framework, better-know-framework (in courtesy of DNR ;)) is part two of my teaching process. First part is teaching my coworkers about LINQ, what it can do for them and how it is written. My big question is where are all the good basic resources for LINQ education, everything if find is tightly coupled to Linq2Sql or all other sorts of material. Neither have I been able to find a tutorial for the actual linq syntax (except a specification of it all). (I hope this haven't been asked before but if it has please say so, cause then my searching skills have failed ;) )

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  • Converting "is null" into a linq to sql statement

    - by Darryl Braaten
    I am having trouble replicating the following sql as a LINQ statement select TableA.* from TableA left outer join TableAinTableB on TableA.Id = TableAId where TableBId is null The following returns no lines from TableA in db.TableA join AinB in db.TableAinTableB on TableA.Id equals TableAId where AinB.TableBId == null select TableA Also tried and a few other things that didn't work. from TableA in db.TableA join AinB in db.TableAinTableB on TableA.Id equals TableAId where AinB == null select TableA TableAinTableB is a many to many table. The query I want will pull all the records from TableA that have no records in the middle table. My sql does what I want but I have no idea how to convert it to LINQ to SQL. I ended up working around it by just doing a db.ExecuteQuery("working sql"); But I would like to know if the query is possible in LINQ and how to write it, or a pointer to a document that covers this scenario. My searching did not uncover anything I found useful.

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  • Unit Testing, IDataContext and Stored Procedures via Linq

    - by Terry_Brown
    hey folks, I'm currently using Stephen Walther's approach to unit testing Linq to SQL and the datacontext (http://stephenwalther.com/blog/archive/2008/08/17/asp-net-mvc-tip-33-unit-test-linq-to-sql.aspx) which is working a treat for all things linq. My Dal layer takes in an IDataContext, I use DI (via Unity) to concrete that up as the correct DataContext object and all works well. But - we have a company policy here of writes going via Stored Procs. Has anyone come up with a solution for mocking/faking the data context and still allowing stored procs to effectively be unit tested? I've got no real experience of any of the mocking frameworks (Rhino etc.) so if these are the correct means of doing this, I'd love some pointers on guides for them. Many thanks, Terry

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  • Linq to sql Error "Data at the root level is invalid " for nullable xml column

    - by Mukesh
    I have Created a table like CREATE TABLE [dbo].[tab1]( [Id] [int] NOT NULL, [Name] [varchar](100) NOT NULL, [Meta] [xml] NULL, CONSTRAINT [PK_tab1] PRIMARY KEY CLUSTERED ( [Id] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] ) ON [PRIMARY] TEXTIMAGE_ON [PRIMARY] When I am doing linq to sql query to fetch a data it throw an error "data at the root level is invalid linq". In further investigation I come to know that the meta column is null in that case. In real it is nullable Do I have to remove the nullable and set some blank root node as default or there is some another way to get rid of the error. My linq Query which throws error var obj1= (from obj in dbContext.tab1s where obj.id== 123 select obj).FirstOrDefault<Tab1>();

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