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  • MSSQL 2005: Update rows in a specified order (like ORDER BY)?

    - by JMTyler
    I want to update rows of a table in a specific order, like one would expect if including an ORDER BY clause, but MS SQL does not support the ORDER BY clause in UPDATE queries. I have checked out this question which supplied a nice solution, but my query is a bit more complicated than the one specified there. UPDATE TableA AS Parent SET Parent.ColA = Parent.ColA + (SELECT TOP 1 Child.ColA FROM TableA AS Child WHERE Child.ParentColB = Parent.ColB ORDER BY Child.Priority) ORDER BY Parent.Depth DESC; So, what I'm hoping that you'll notice is that a single table (TableA) contains a hierarchy of rows, wherein one row can be the parent or child of any other row. The rows need to be updated in order from the deepest child up to the root parent. This is because TableA.ColA must contain an up-to-date concatenation of its own current value with the values of its children (I realize this query only concats with one child, but that is for the sake of simplicity - the purpose of the example in this question does not necessitate any more verbosity), therefore the query must update from the bottom up. The solution suggested in the question I noted above is as follows: UPDATE messages SET status=10 WHERE ID in (SELECT TOP (10) Id FROM Table WHERE status=0 ORDER BY priority DESC ); The reason that I don't think I can use this solution is because I am referencing column values from the parent table inside my subquery (see WHERE Child.ParentColB = Parent.ColB), and I don't think two sibling subqueries would have access to each others' data. So far I have only determined one way to merge that suggested solution with my current problem, and I don't think it works. UPDATE TableA AS Parent SET Parent.ColA = Parent.ColA + (SELECT TOP 1 Child.ColA FROM TableA AS Child WHERE Child.ParentColB = Parent.ColB ORDER BY Child.Priority) WHERE Parent.Id IN (SELECT Id FROM TableA ORDER BY Parent.Depth DESC); The WHERE..IN subquery will not actually return a subset of the rows, it will just return the full list of IDs in the order that I want. However (I don't know for sure - please tell me if I'm wrong) I think that the WHERE..IN clause will not care about the order of IDs within the parentheses - it will just check the ID of the row it currently wants to update to see if it's in that list (which, they all are) in whatever order it is already trying to update... Which would just be a total waste of cycles, because it wouldn't change anything. So, in conclusion, I have looked around and can't seem to figure out a way to update in a specified order (and included the reason I need to update in that order, because I am sure I would otherwise get the ever-so-useful "why?" answers) and I am now hitting up Stack Overflow to see if any of you gurus out there who know more about SQL than I do (which isn't saying much) know of an efficient way to do this. It's particularly important that I only use a single query to complete this action. A long question, but I wanted to cover my bases and give you guys as much info to feed off of as possible. :) Any thoughts?

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  • PHP output of foreach loop into a new array.

    - by RobHardgood
    I know I'm probably missing something easy, but I have a foreach loop and I'm trying to modify the values of the first array, and output a new array with the modifications as the new values. Basically I'm starting with an array: 0 = A:B 1 = B:C 2 = C:D And I'm using explode() to strip out the :'s and second letters, so I want to be left with an array: 0 = A 1 = B 2 = C The explode() part of my function works fine, but I only seem to get single string outputs. A, B, and C.

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  • Azure table storage: maximum variable size ?

    - by Egon
    I will be using the table storage to store a lot of blob names, in a single string, appended to each other using some special character. This string will sky rockets pretty soon. But is there a maximum size to the length of a property for a particular entity ? in my case the string ?

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  • Match Regex across newlines?

    - by Jörg Battermann
    I have a regex ( "(&lt;lof&lt;).*?(&gt;&gt;)" ) that works and matches perfectly on single line input. However, if the input contains newlines between the two () parts it does not match at all. What's the best way to ignore any newlines at all in that case?

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  • Need help in Select query..

    - by Parth
    If I have four rows for a field with different values with other fields similar and then other four rows with same condition, as given below here u can see there different rows for insert with only difference in the "newvalue" and "field" excluding "id" for the table_name=jos_menu, operation=INSERT and live=0 now here what select query should be used to get only single row from the table on every change of table_name...??

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  • What are the Options for Storing Hierarchical Data in a Relational Database?

    - by orangepips
    Good Overviews One more Nested Intervals vs. Adjacency List comparison: the best comparison of Adjacency List, Materialized Path, Nested Set and Nested Interval I've found. Models for hierarchical data: slides with good explanations of tradeoffs and example usage Representing hierarchies in MySQL: very good overview of Nested Set in particular Hierarchical data in RDBMSs: most comprehensive and well organized set of links I've seen, but not much in the way on explanation Options Ones I am aware of and general features: Adjacency List: Columns: ID, ParentID Easy to implement. Cheap node moves, inserts, and deletes. Expensive to find level (can store as a computed column), ancestry & descendants (Bridge Hierarchy combined with level column can solve), path (Lineage Column can solve). Use Common Table Expressions in those databases that support them to traverse. Nested Set (a.k.a Modified Preorder Tree Traversal) First described by Joe Celko - covered in depth in his book Trees and Hierarchies in SQL for Smarties Columns: Left, Right Cheap level, ancestry, descendants Compared to Adjacency List, moves, inserts, deletes more expensive. Requires a specific sort order (e.g. created). So sorting all descendants in a different order requires additional work. Nested Intervals Combination of Nested Sets and Materialized Path where left/right columns are floating point decimals instead of integers and encode the path information. Bridge Table (a.k.a. Closure Table: some good ideas about how to use triggers for maintaining this approach) Columns: ancestor, descendant Stands apart from table it describes. Can include some nodes in more than one hierarchy. Cheap ancestry and descendants (albeit not in what order) For complete knowledge of a hierarchy needs to be combined with another option. Flat Table A modification of the Adjacency List that adds a Level and Rank (e.g. ordering) column to each record. Expensive move and delete Cheap ancestry and descendants Good Use: threaded discussion - forums / blog comments Lineage Column (a.k.a. Materialized Path, Path Enumeration) Column: lineage (e.g. /parent/child/grandchild/etc...) Limit to how deep the hierarchy can be. Descendants cheap (e.g. LEFT(lineage, #) = '/enumerated/path') Ancestry tricky (database specific queries) Database Specific Notes MySQL Use session variables for Adjacency List Oracle Use CONNECT BY to traverse Adjacency Lists PostgreSQL ltree datatype for Materialized Path SQL Server General summary 2008 offers HierarchyId data type appears to help with Lineage Column approach and expand the depth that can be represented.

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  • C# Select clause returns system exception instead of relevant object

    - by Kashif
    I am trying to use the select clause to pick out an object which matches a specified name field from a database query as follows: objectQuery = from obj in objectList where obj.Equals(objectName) select obj; In the results view of my query, I get: base {System.SystemException} = {"Boolean Equals(System.Object)"} Where I should be expecting something like a Car, Make, or Model Would someone please explain what I am doing wrong here? The method in question can be seen here: // this function searches the database's table for a single object that matches the 'Name' property with 'objectName' public static T Read<T>(string objectName) where T : IEquatable<T> { using (ISession session = NHibernateHelper.OpenSession()) { IQueryable<T> objectList = session.Query<T>(); // pull (query) all the objects from the table in the database int count = objectList.Count(); // return the number of objects in the table // alternative: int count = makeList.Count<T>(); IQueryable<T> objectQuery = null; // create a reference for our queryable list of objects T foundObject = default(T); // create an object reference for our found object if (count > 0) { // give me all objects that have a name that matches 'objectName' and store them in 'objectQuery' objectQuery = from obj in objectList where obj.Equals(objectName) select obj; // make sure that 'objectQuery' has only one object in it try { foundObject = (T)objectQuery.Single(); } catch { return default(T); } // output some information to the console (output screen) Console.WriteLine("Read Make: " + foundObject.ToString()); } // pass the reference of the found object on to whoever asked for it return foundObject; } } Note that I am using the interface "IQuatable<T>" in my method descriptor. An example of the classes I am trying to pull from the database is: public class Make: IEquatable<Make> { public virtual int Id { get; set; } public virtual string Name { get; set; } public virtual IList<Model> Models { get; set; } public Make() { // this public no-argument constructor is required for NHibernate } public Make(string makeName) { this.Name = makeName; } public override string ToString() { return Name; } // Implementation of IEquatable<T> interface public virtual bool Equals(Make make) { if (this.Id == make.Id) { return true; } else { return false; } } // Implementation of IEquatable<T> interface public virtual bool Equals(String name) { if (this.Name.Equals(name)) { return true; } else { return false; } } } And the interface is described simply as: public interface IEquatable<T> { bool Equals(T obj); }

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  • How do you prevent IDisposable from spreading to all your classes?

    - by GrahamS
    Start with these simple classes... Let's say I have a simple set of classes like this: class Bus { Driver busDriver = new Driver(); } class Driver { Shoe[] shoes = { new Shoe(), new Shoe() }; } class Shoe { Shoelace lace = new Shoelace(); } class Shoelace { bool tied = false; } A Bus has a Driver, the Driver has two Shoes, each Shoe has a Shoelace. All very silly. Add an IDisposable object to Shoelace Later I decide that some operation on the Shoelace could be multi-threaded, so I add an EventWaitHandle for the threads to communicate with. So Shoelace now looks like this: class Shoelace { private AutoResetEvent waitHandle = new AutoResetEvent(false); bool tied = false; // ... other stuff .. } Implement IDisposable on Shoelace Buit now FxCop will complain: "Implement IDisposable on 'Shoelace' because it creates members of the following IDisposable types: 'EventWaitHandle'." Okay, I implement IDisposable on Shoelace and my neat little class becomes this horrible mess: class Shoelace : IDisposable { private AutoResetEvent waitHandle = new AutoResetEvent(false); bool tied = false; private bool disposed = false; public void Dispose() { Dispose(true); GC.SuppressFinalize(this); } ~Shoelace() { Dispose(false); } protected virtual void Dispose(bool disposing) { if (!this.disposed) { if (disposing) { if (waitHandle != null) { waitHandle.Close(); waitHandle = null; } } // No unmanaged resources to release otherwise they'd go here. } disposed = true; } } Or (as pointed out by commenters) since Shoelace itself has no unmanaged resources, I might use the simpler dispose implementation without needing the Dispose(bool) and Destructor: class Shoelace : IDisposable { private AutoResetEvent waitHandle = new AutoResetEvent(false); bool tied = false; public void Dispose() { if (waitHandle != null) { waitHandle.Close(); waitHandle = null; } GC.SuppressFinalize(this); } } Watch in horror as IDisposable spreads Right that's that fixed. But now FxCop will complain that Shoe creates a Shoelace, so Shoe must be IDisposable too. And Driver creates Shoe so Driver must be IDisposable. and Bus creates Driver so Bus must be IDisposable and so on. Suddenly my small change to Shoelace is causing me a lot of work and my boss is wondering why I need to checkout Bus to make a change to Shoelace. The Question How do you prevent this spread of IDisposable, but still ensure that your unmanaged objects are properly disposed?

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  • Update the rank in a MySQL Table

    - by sammichy
    I have the following table structure for a table Player Table Player { Long playerID; Long points; Long rank; } Assuming that the playerID and the points have valid values, can I update the rank for all the players based on the number of points in a single query? If two people have the same number of points, they should tie for the rank.

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  • Entity Framework looking for wrong column

    - by m.edmondson
    I'm brand new to the Entity Framework and trying to learn all it can offer. I'm currently working my way through the MVC Music Store tutorial which includes the following code: public ActionResult Browse(string genre) { // Retrieve Genre and its Associated Albums from database var genreModel = storeDB.Genres.Include("Albums") .Single(g => g.Name == genre); return View(genreModel); } as I'm working in VB I converted it like so: Function Browse(ByVal genre As String) As ActionResult 'Retrieve Genre and its Associated Albums from database Dim genreModel = storeDB.Genres.Include("Albums"). _ Single(Function(g) g.Name = genre) Return(View(genreModel)) End Function The problem is I'm getting the following exception: Invalid column name 'GenreGenreId'. Which I know is true, but I can't for the life of my work out where it's getting 'GenreGenreId' from. Probably a basic question but I'll appreciate any help in the right direction. As per requested here is the source for my classes: Album.vb Public Class Album Private _title As String Private _genre As Genre Private _AlbumId As Int32 Private _GenreId As Int32 Private _ArtistId As Int32 Private _Price As Decimal Private _AlbumArtUrl As String Public Property Title As String Get Return _title End Get Set(ByVal value As String) _title = value End Set End Property Public Property AlbumId As Int16 Get Return _AlbumId End Get Set(ByVal value As Int16) _AlbumId = value End Set End Property Public Property GenreId As Int16 Get Return _GenreId End Get Set(ByVal value As Int16) _GenreId = value End Set End Property Public Property ArtistId As Int16 Get Return _ArtistId End Get Set(ByVal value As Int16) _ArtistId = value End Set End Property Public Property AlbumArtUrl As String Get Return _AlbumArtUrl End Get Set(ByVal value As String) _AlbumArtUrl = value End Set End Property Public Property Price As Decimal Get Return _Price End Get Set(ByVal value As Decimal) _Price = value End Set End Property Public Property Genre As Genre Get Return _genre End Get Set(ByVal value As Genre) _genre = value End Set End Property End Class Genre.vb Public Class Genre Dim _genreId As Int32 Dim _Name As String Dim _Description As String Dim _Albums As List(Of Album) Public Property GenreId As Int32 Get Return _genreId End Get Set(ByVal value As Int32) _genreId = value End Set End Property Public Property Name As String Get Return _Name End Get Set(ByVal value As String) _Name = value End Set End Property Public Property Description As String Get Return _Description End Get Set(ByVal value As String) _Description = value End Set End Property Public Property Albums As List(Of Album) Get Return _Albums End Get Set(ByVal value As List(Of Album)) _Albums = value End Set End Property End Class MusicStoreEntities.vb Imports System.Data.Entity Namespace MvcApplication1 Public Class MusicStoreEntities Inherits DbContext Public Property Albums As DbSet(Of Album) Public Property Genres As DbSet(Of Genre) End Class End Namespace

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  • Best language for scripting large scale file management

    - by Dan
    The National Park Service's Natural Sounds Program collects multiple terabytes of data each year measuring soundscapes. In your opinion, what is best available scripting language to manage massive amounts of files and file types? We would like to easily design and run efficient user-friendly scripts to search for and retrieve/create copies of files that may be located in different directories according a single static hierarchy. The OS will most likely be windows. Thanks!

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  • Create a CBitmap from Resources ID

    - by Smashery
    I need to fill a CImageList with a number of bitmaps which are stored in separate bmp files (rather than as a single bmp with numerous parts). I assume I need to create a CBitmap so I can call the Add method of CImageList. So how might one create a CBitmap object using only MFC Resource IDs?

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  • VB6 ADO Command to SQL Server

    - by Emtucifor
    I'm getting an inexplicable error with an ADO command in VB6 run against a SQL Server 2005 database. Here's some code to demonstrate the problem: Sub ADOCommand() Dim Conn As ADODB.Connection Dim Rs As ADODB.Recordset Dim Cmd As ADODB.Command Dim ErrorAlertID As Long Dim ErrorTime As Date Set Conn = New ADODB.Connection Conn.ConnectionString = "Provider=SQLOLEDB.1;Integrated Security=SSPI;Initial Catalog=database;Data Source=server" Conn.CursorLocation = adUseClient Conn.Open Set Rs = New ADODB.Recordset Rs.CursorType = adOpenStatic Rs.LockType = adLockReadOnly Set Cmd = New ADODB.Command With Cmd .Prepared = False .CommandText = "ErrorAlertCollect" .CommandType = adCmdStoredProc .NamedParameters = True .Parameters.Append .CreateParameter("@ErrorAlertID", adInteger, adParamOutput) .Parameters.Append .CreateParameter("@CreateTime", adDate, adParamOutput) Set .ActiveConnection = Conn Rs.Open Cmd ErrorAlertID = .Parameters("@ErrorAlertID").Value ErrorTime = .Parameters("@CreateTime").Value End With Debug.Print Rs.State ' Shows 0 - Closed Debug.Print Rs.RecordCount ' Of course this fails since the recordset is closed End Sub So this code was working not too long ago but now it's failing on the last line with the error: Run-time error '3704': Operation is not allowed when the object is closed Why is it closed? I just opened it and the SP returns rows. I ran a trace and this is what the ADO library is actually submitting to the server: declare @p1 int set @p1=1 declare @p2 datetime set @p2=''2010-04-22 15:31:07:770'' exec ErrorAlertCollect @ErrorAlertID=@p1 output,@CreateTime=@p2 output select @p1, @p2 Running this as a separate batch from my query editor yields: Msg 102, Level 15, State 1, Line 4 Incorrect syntax near '2010'. Of course there's an error. Look at the double single quotes in there. What the heck could be causing that? I tried using adDBDate and adDBTime as data types for the date parameter, and they give the same results. When I make the parameters adParamInputOutput, then I get this: declare @p1 int set @p1=default declare @p2 datetime set @p2=default exec ErrorAlertCollect @ErrorAlertID=@p1 output,@CreateTime=@p2 output select @p1, @p2 Running that as a separate batch yields: Msg 156, Level 15, State 1, Line 2 Incorrect syntax near the keyword 'default'. Msg 156, Level 15, State 1, Line 4 Incorrect syntax near the keyword 'default'. What the heck? SQL Server doesn't support this kind of syntax. You can only use the DEFAULT keyword in the actual SP execution statement. I should note that removing the extra single quotes from the above statement makes the SP run fine. ... Oh my. I just figured it out. I guess it's worth posting anyway.

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  • Android Convert Video To MP4

    - by Isaac Waller
    I have a Android app. It recieves videos in .flv format which is unplayable by the Android phone. I was wondering how to convert the file to MP4. I could use FFMPEG, but I do not know how I would get it onto the phone, and how it would work on multiple phones if it was compiled for a single one.

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  • Handling exceptions raised in observers

    - by sparky
    I have a Rails (2.3.5) application where there are many groups, and each Group has_many People. I have a Group edit form where users can create new people. When a new person is created, they are sent an email (the email address is user entered on the form). This is accomplished with an observer on the Person model. The problem comes when ActionMailer throws an exception - for example if the domain does not exist. Clearly that cannot be weeded out with a validation. There would seem to be 2 ways to deal with this: A begin...rescue...end block in the observer around the mailer. The problem with this is that the only way to pass any feedback to the user would be to set a global variable - as the observer is out of the MVC flow, I can't even set a flash[:error] there. A rescue_from in the Groups controller. This works fine, but has 2 problems. Firstly, there is no way to know which person threw the exception (all I can get is the 503 exception, no way to know which person caused the problem). This would be useful information to be able to pass back to the user - at the moment, there is no way for me to let them know which email address is the problem - at the moment, I just have to chuck the lot back at them, and issue an unhelpful message saying that one of them is not correct. Secondly (and to a certain extent this make the first point moot) it seems that it is necessary to call a render in the rescue_from, or it dies with a rather bizarre "can't convert Array into String" error from webbrick, with no stack trace & nothing in the log. Thus, I have to throw it back to the user when I come across the first error and have to stop processing the rest of the emails. Neither of the solutions are optimal. It would seem that the only way to get Rails to do what I want is option 1, and loathsome global variables. This would also rely on Rails being single threaded. Can anyone suggest a better solution to this problem?

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  • How can I add multiple pre-commit SVN Hooks

    - by Alister Bulman
    I've got several pre-commit hooks that I would like to run before each commit. Right now, they are all just shell-scripts, so I know i could just concatenate them to get them all to run. In the future though, additional scripts may be written in Perl, PHP, or some other language as well. How can I run several different scripts as part of a single pre-commit hook?

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  • Implement python replace() function without using regexp

    - by jwesonga
    I'm trying to rewrite the equivalent of the python replace() function without using regexp. Using this code, i've managed to get it to work with single chars, but not with more than one character: def Replacer(self, find_char, replace_char): s = [] for char in self.base_string: if char == find_char: char = replace_char #print char s.append(char) s = ''.join(s) my_string.Replacer('a','E') Anybody have any pointers how to make this work with more than one character? example: my_string.Replacer('kl', 'lll')

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  • How to generate spectrum color palettes

    - by ddimitrov
    Is there an easy way to convert between color models in Java (RGB, HSV and Lab). Assuming RGB color model: How do I calculate black body spectrum color palette? I want to use it for a heatmap chart. How about single-wavelength spectrum? Edit: I found that the ColorSpace class can be used for conversions between RGB/CIE and many other color models.

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