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  • Which way is more effective?

    - by Danny Chen
    I have a huge IEnumerable(suppose the name is myItems), which way is more effective? Solution 1: Filter it first then ForEach. Array.ForEach(myItems.Where(FILTER-IT-HERE).ToArray(),MY-ACTION); Solution 2: Do RETURN in MY-ACTION if the item is not up to the mustard. Array.ForEach(myItems.ToArray(),MY-ACTION-WITH-FILTER); Is one of them always better than another? Or any other good suggestions? Thanks in advance.

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  • How do I simulate "Is In" using Linq2Sql

    - by flipdoubt
    I often find myself with a list of disconnected Linq2Sql objects or keys that I need to re-select from a Linq2Sql data-context to update or delete in the database. If this were SQL, I would use IS IN in the SQL WHERE clause, but I am stuck with what to do in Linq2Sql. Here is a sample of what I would like to write: public void MarkValidated(IList<int> idsToValidate) { using(_Db.NewSession()) // Instatiates new DataContext { // ThatAreIn <- this is where I am stuck var items = _Db.Items.ThatAreIn(idsToValidate).ToList(); foreach(var item in items) item.Validated = DateTime.Now; _Db.SubmitChanges(); } // Disposes of DataContext } Or: public void DeleteItems(IList<int> idsToDelete) { using(_Db.NewSession()) // Instatiates new DataContext { // ThatAreIn <- this is where I am stuck var items = _Db.Items.ThatAreIn(idsToValidate); _Db.Items.DeleteAllOnSubmit(items); _Db.SubmitChanges(); } // Disposes of DataContext } Can I get this done in one trip to the database? If so, how? Is it possible to send all those ints to the database as a list of parameters and is that more efficient than doing a foreach over the list to select each item one at a time?

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  • How to write a SQL query for numerous conditions with lots of fields in ASP.NET

    - by Yongwei Xing
    Hi all I have a ASP.NET site. There is a table in the SQL Server with more than 30 fields. I need make a page on which there are many filters to query data from database based on the filters you select or input. One filter for one fields in the database. The filter would be dropdown list, textbox,checkbox or listbox. If you do not choose one filter, it means select all for this field. So there are lots of combination for these fields. Is there any simple way to write such page and query for this requirement? Best Regards,

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  • "Row not found or changed" Problem

    - by winston schröder
    Hi there, I'm working on a SQL CE Database and get into the "Row nor found or changed" exception. The exception only occurs when I try to update. On the first Run after the insert it shows up a MemberChangeConflict which says, that my Column Created_at has in all three values (current, original, database) the same. But in a second attempt it doesn't appear anymore. The DataContext is instanciated on Startup and freed on Exit of my Local(!) Application. I use a sqlmetal generated mapping and code file. In the map I added some Associations and set the timemstamp columns UpdateCheck property to Always while all other have the setting never. The Timestamp Column is marked as isVersion="true", the Id Column as Primary Key. Since I don't dispose the datacontext I expected to be using implicit transaction. When I run the SubmitChanges Method within a TransactionScope. Can anyone tell me how I can update the timestamp within the code ? I know about the Problems one has to deal with if you dispose the datacontext. So I decided not to do this since I use a Single User Local DB Cache File. (I did already use a version where I disposed the datacontext after every usage, but this version had a real bad performance and error rate, so I decided to choose the other variant.) LibDB.Client.Vehicles tmp = null; try { tmp = e.Parameter as LibDB.Client.Vehicles; if (tmp == null) return; if (!this._dc.Vehicles.Contains(tmp)) { this._dc.Vehicles.Attach(tmp); } this.ShowChangesReport(this._dc.GetChangeSet()); using (TransactionScope ts = new TransactionScope()) { try { this._dc.SubmitChanges(); ts.Complete(); } catch (ChangeConflictException cce) { Console.WriteLine("Optimistic concurrency error."); Console.WriteLine(cce.Message); Console.ReadLine(); foreach (ObjectChangeConflict occ in this._dc.ChangeConflicts) { MetaTable metatable = this._dc.Mapping.GetTable(occ.Object.GetType()); LibDB.Client.Vehicles entityInConflict = (LibDB.Client.Vehicles)occ.Object; Console.WriteLine("Table name: {0}", metatable.TableName); Console.Write("Vin: "); Console.WriteLine(entityInConflict.Vin); foreach (MemberChangeConflict mcc in occ.MemberConflicts) { object currVal = mcc.CurrentValue; object origVal = mcc.OriginalValue; object databaseVal = mcc.DatabaseValue; MemberInfo mi = mcc.Member; Console.WriteLine("Member: {0}", mi.Name); Console.WriteLine("current value: {0}", currVal); Console.WriteLine("original value: {0}", origVal); Console.WriteLine("database value: {0}", databaseVal); } throw cce; } } catch (Exception ex) { this.ShowChangeConflicts(this._dc.ChangeConflicts); Console.WriteLine(ex.Message); } } this.ShowChangesReport(this._dc.GetChangeSet());

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  • C# XElement: Node Formatting with HTML

    - by Arnej65
    I'm extracting XML node from an XElement. When I use XElement.Value it strips any HTML that may be in the node. I know that if I do XElement.ToString() I can keep the HTML, but it also gives me the node tags. Is there any way to extract the content of a Node as is without the HTML being stripped out? Cheers.

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  • Linqify this: Aggregate a subset of a list

    - by JMarsch
    Suppose I have a list or array of items, and I want to sum a subset of the items in the list. (in my case, it happens to always be a sequential subset). Here's the old-fashioned way: int sum = 0; for(int i = startIndex; i <= stopIndex; i++) sum += myList[i].TheValue; return sum; What's the best way to linqify that code?

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  • ASP.NET MVC- Bizarre problem - suddennly lost all LINQTO SQL data context objects

    - by MikeD
    I was making an edit to a long existing project. Specifically I added some fields to a table and had to delete the table from the LINQTOSQL designer and re-add it. doesn't Also had to do the same for a view. Mode some other code changes and went to build . Now my project won't build because it can't resolve any of the data context objects (all tables and views) in my code. I don't know what I did or how this happeened. I have many tables and views in the project's L2S data context so I don't wont to try and do over. Please any suggestions on how to resolve this problem are greatly appreciated. Desparate! The error messages I am getting are the familiar The type or namespace name 'equipment' could not be found (are you missing a using directive or an assembly reference?)

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  • Change C# sorting behaviour

    - by Erik
    Lets say i have the strings abc_ and abc2_. Now, normally when sorting i C# abc2_ would come after abc_, leaving the result: abc_ abc2_ I am using this to sort, if it matters: var element = from c in elements orderby c.elementName ascending select c; How can i change this? I want abc_ to come last. Reversing is not an option because the list is contains more than two elements.

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  • problem with a join

    - by Luca Romagnoli
    I have this code: int se = (int) settings.GruppoSegreteria; var acc = db.USR_Accounts.Where( p => p.ID_Gruppo == se); var segreterie = from s in db.USR_Utenti join h in acc on s.ID equals h.USR_UtentiReference select s; And this error: The type of one of the expressions in the join clause is incorrect. Type inference failed in the call to 'Join' I don't understand it. Can you help me? thanks

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  • Precompile Lambda Expression Tree conversions as constants?

    - by Nathan
    It is fairly common to take an Expression tree, and convert it to some other form, such as a string representation (for example this question and this question, and I suspect Linq2Sql does something similar). In many cases, perhaps even most cases, the Expression tree conversion will always be the same, i.e. if I have a function public string GenerateSomeSql(Expression<Func<TResult, TProperty>> expression) then any call with the same argument will always return the same result for example: GenerateSomeSql(x => x.Age) //suppose this will always return "select Age from Person" GenerateSomeSql(x => x.Ssn) //suppose this will always return "select Ssn from Person" So, in essence, the function call with a particular argument is really just a constant, except time is wasted at runtime re-computing it continuously. Assuming, for the sake of argument, that the conversion was sufficiently complex to cause a noticeable performance hit, is there any way to pre-compile the function call into an actual constant?

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  • Entity Date Modelset Generates Errors in Visual Web Developer

    - by davemackey
    I attempted to add a ADO.NET Entity Data Model to my Visual Web Developer 2010 Express project and it generates but returns a whole slew of errors. Why is this generating errors? Here are the main errors: 'Public Property ID As Integer' has multiple definitions with identical signatures. Method 'Onaddress_IDChanging' cannot be declared 'Partial' because only one method 'Onaddress_IDChanging' can be marked 'Partial'. '_line1' is already declared as 'Private _line1 As String' in this class.

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  • Multiple join query in eSql

    - by Syma
    Hi guys, This is my first question in stackoverflow but really not the first time to get solution here. I am struggling with multiple join in entity framework 4. I have three tables (Accounts, Users and AccountUsers) that am finding difficult to query. What I want is to get all the users for the provided accountId including the account creator. I can get all the account users with no problem but the hard side for me is getting the account creator since it's not added to AccountUsers table. below is a quick preview how the tables are related. Accounts AccountId UserId (account creator) ...other columns Users UserId ...other columns AccountUsers AccountId UserId I would prefer the query to be esql, but Linq to Entities will do. I trust you guys on stackoverflow, so I know this won't take long to get the 'Answer' mark. Thanks for even reading.

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  • JPA optimistic lock - setting @Version to entity class cause query to include VERSION as column

    - by masato-san
    I'm using JPA Toplink Essential, Netbean6.8, GlassFish v3 In my Entity class I added @Version annotation to enable optimistic locking at transaction commit however after I added the annotation, my query started including VERSION as column thus throwing SQL exception. None of this is mentioned in any tutorial I've seen so far. What could be wrong? Snippet public class MasatosanTest2 implements Serializable { private static final long serialVersionUID = 1L; @Id @Basic(optional = false) @Column(name = "id") private Integer id; @Column(name = "username") private String username; @Column(name = "note") private String note; //here adding Version @Version int version; query used: SELECT m FROM MasatosanTest2 m Internal Exception: com.microsoft.sqlserver.jdbc.SQLServerException Call: SELECT id, username, note, VERSION FROM MasatosanTest2

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  • Zend Framework - applying order by on a nested query

    - by Gublooo
    Hey guys This might be a very simple thing. Check out the normal sql query below (select * from shopping order by shopping_id desc limit 5) order by RAND() This query runs successfully in mysql - not sure if this is the right way of doing it - but it works. It gets the last 5 ids from shopping table and randomly orders them everytime I want to achieve this in Zend. I'm not sure how to execute the first part and then apply the RAND clause to the results - what I have below does not do that. $select = $this-select() -from(array('sh'='shopping')) -order('shopping_id desc') -limit(5) -order('RAND()');

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  • MVC and positional parameters in a query string

    - by Pete Nelson
    This is more of a question to satisfy my curiosity vs something I really need answered. Back in ASP.NET WebForms, I'd occasionally use a positional parameter in a query string if I only had to pass one thing to a page. For example: http://localhost/site/MyPage.aspx?ABCD1234 Then my code would look like this: string accountNumber = ""; if (Request.QueryString.Count > 0) accountNumber = Request.QueryString[0]; In MVC, can you pass a positional query string parameter to a controller method instead of accessing it through Request.QueryString?

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  • SQL Server - Query Short-Circuiting?

    - by Sam Schutte
    Do T-SQL queries in SQL Server support short-circuiting? For instance, I have a situation where I have two database and I'm comparing data between the two tables to match and copy some info across. In one table, the "ID" field will always have leading zeros (such as "000000001234"), and in the other table, the ID field may or may not have leading zeros (might be "000000001234" or "1234"). So my query to match the two is something like: select * from table1 where table1.ID LIKE '%1234' To speed things up, I'm thinking of adding an OR before the like that just says: table1.ID = table2.ID to handle the case where both ID's have the padded zeros and are equal. Will doing so speed up the query by matching items on the "=" and not evaluating the LIKE for every single row (will it short circuit and skip the LIKE)?

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  • Nhibernate criteria query inserts an extra order by expression when using JoinType.LeftOuterJoin and Projections

    - by Aaron Palmer
    Why would this nhibernate criteria query produce the sql query below? return Session.CreateCriteria(typeof(FundingCategory), "fc") .CreateCriteria("FundingPrograms", "fp") .CreateCriteria("Projects", "p", JoinType.LeftOuterJoin) .Add(Restrictions.Disjunction() .Add(Restrictions.Eq("fp.Recipient.Id", recipientId)) .Add(Restrictions.Eq("p.Recipient.Id", recipientId)) ) .SetProjection(Projections.ProjectionList() .Add(Projections.GroupProperty("fc.Name"), "fcn") .Add(Projections.Sum("fp.ObligatedAmount"), "fpo") .Add(Projections.Sum("p.ObligatedAmount"), "po") ) .AddOrder(Order.Desc("fpo")) .AddOrder(Order.Desc("po")) .AddOrder(Order.Asc("fcn")) .List<object[]>(); SELECT this_.Name as y0_, sum(fp1_.ObligatedAmount) as y1_, sum(p2_.ObligatedAmount) as y2_ FROM fundingCategories this_ inner join fundingPrograms fp1_ on this_.fundingCategoryId = fp1_.fundingCategoryId left outer join projects p2_ on fp1_.fundingProgramId = p2_.fundingProgramId WHERE (fp1_.recipientId = 6 /* @p0 */ or p2_.recipientId = 6 /* @p1 */) GROUP BY this_.Name ORDER BY p2_.name asc, y1_ desc, y2_ desc, y0_ asc It is incorrectly putting the p2_name asc into the ORDER BY statement, and causing it to crash. This only happens when I use JoinType.LeftOuterJoin on my Projects criteria. Is this a known nhibernate bug? I'm using nhibernate 2.0.1.4000. Thanks for any insight.

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  • XDocument holding onto Memory?

    - by Jon
    I have an appplication that does a XDocument.Load from a 20mb file and then gets passed to a form to view its contents: openFileDialog1.FileName = ""; if (openFileDialog1.ShowDialog() == DialogResult.OK) { AuditFile = XDocument.Load(openFileDialog1.FileName); fmAuditLogViewer AuditViewer = new fmAuditLogViewer(); AuditViewer.ReportDocument = AuditFile; AuditViewer.Init(); AuditViewer.ShowDialog(); AuditViewer.Dispose(); AuditFile.RemoveNodes(); AuditFile = null; } In Task Manager I can see the memory being used by my application shoot up when I open this file. When I have finished viewing this file in my application I call : myXDocument.RemoveNodes(); myXDocument = null; However the memory use in Task Manager is still pretty high against my app. Is the XDocument still being held in memory and can I decrease the memory usage by my app?

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  • Using Linq2Sql to insert data into multiple tables using an auto incremented primary key

    - by Thomas
    I have a Customer table with a Primary key (int auto increment) and an Address table with a foreign key to the Customer table. I am trying to insert both rows into the database in one nice transaction. using (DatabaseDataContext db = new DatabaseDataContext()) { Customer newCustomer = new Customer() { Email = customer.Email }; Address b = new Address() { CustomerID = newCustomer.CustomerID, Address1 = billingAddress.Address1 }; db.Customers.InsertOnSubmit(newCustomer); db.Addresses.InsertOnSubmit(b); db.SubmitChanges(); } When I run this I was hoping that the Customer and Address table automatically had the correct keys in the database since the context knows this is an auto incremented key and will do two inserts with the right key in both tables. The only way I can get this to work would be to do SubmitChanges() on the Customer object first then create the address and do SubmitChanges() on that as well. This would create two roundtrips to the database and I would like to see if I can do this in one transaction. Is it possible? Thanks

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  • Oracle - Parameterized Query has EXECUTIONS = PARSE_CALLS

    - by Cory Grimster
    We have a .NET application talking to Oracle 10g. Our DBA recently pulled a list of queries where executions is equal to parse_calls. We assumed that this would help us find all of the unparameterized queries in our code. Unexpectedly, the following query showed up near the top of this list, with 1,436,169 executions and 1,436,151 parses: SELECT bar.foocolumn FROM bartable bar, baztable baz WHERE bar.some_id = :someId AND baz.another_id = :anotherId AND baz.some_date BETWEEN bar.start_date AND (nvl(bar.end_date, baz.some_date + (1/84600)) - (1/84600)) Why is executions equal to parse_calls for this query?

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  • LINQtoSQL Custom Constructor off Partial Class?

    - by sah302
    Hi all, I read this question here: http://stackoverflow.com/questions/82409/is-there-a-way-to-override-the-empty-constructor-in-a-class-generated-by-linqtosq Typically my constructor would look like: public User(String username, String password, String email, DateTime birthday, Char gender) { this.Id = Guid.NewGuid(); this.DateCreated = this.DateModified = DateTime.Now; this.Username = username; this.Password = password; this.Email = email; this.Birthday = birthday; this.Gender = gender; } However, as read in that question, you want to use partial method OnCreated() instead to assign values and not overwrite the default constructor. Okay so I got this : partial void OnCreated() { this.Id = Guid.NewGuid(); this.DateCreated = this.DateModified = DateTime.Now; this.Username = username; this.Password = password; this.Email = email; this.Birthday = birthday; this.Gender = gender; } However, this gives me two errors: Partial Methods must be declared private. Partial Methods must have empty method bodies. Alright I change it to Private Sub OnCreated() to remove both of those errors. However I am still stuck with...how can I pass it values as I would with a normal custom constructor? Also I am doing this in VB (converted it since I know most know/prefer C#), so would that have an affect on this?

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