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  • SharePoint Web Part Constructor Fires Twice When Adding it to the Page (and has a different security

    - by Damon
    We had some exciting times debugging an interesting issue with SharePoint 2007 Web Parts.  We had some code in staging that had been running just fine for weeks and had not been touched or changed in about the same amount of time.  However, when we tried to move the web part into a different staging environment, the part started throwing a security exception when we tried to add it to a page.  After a bit of debugging, we determined that the web part was throwing the exception while trying to access the SPGroups property on the SharePoint site.  This was pretty strange because we were logged in as an admin and the code was working perfectly fine before.  During the debugging process, however, we found out that the web part constructor was being fired twice.  On one request, the security context did not seem to have everything it needed in order to run.  On the other request, the security context was populated with the user context with the user making the request (like it normally is).  Moving the security code outside of the constructor seems to have fixed the issue. Why the discrepancy between the two staging environments?  Turns out we deployed the part originally, then deployed an update with the security code.  Since the part was never "added" to the page after the code updates were made (we just deployed a new assembly to make the updates), we never saw the problem.  It seems as though the constructor fires twice when you are adding the web part to the page, and when you run the web part from the web part gallery.  My only thought on why this would occur is that SharePoint is instantiating an instance to get some information from it - which is odd because you would think that would happen with reflection without requiring a new object.  Anyway, the work around is to just not put anything security related inside the constructor, or to do a good job accounting for the possibility of the security context not being present if you are adding the item to the page. Technorati Tags: SharePoint,.NET,Microsoft,ASP.NET

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  • Why enumerator structs are a really bad idea

    - by Simon Cooper
    If you've ever poked around the .NET class libraries in Reflector, I'm sure you would have noticed that the generic collection classes all have implementations of their IEnumerator as a struct rather than a class. As you will see, this design decision has some rather unfortunate side effects... As is generally known in the .NET world, mutable structs are a Very Bad Idea; and there are several other blogs around explaining this (Eric Lippert's blog post explains the problem quite well). In the BCL, the generic collection enumerators are all mutable structs, as they need to keep track of where they are in the collection. This bit me quite hard when I was coding a wrapper around a LinkedList<int>.Enumerator. It boils down to this code: sealed class EnumeratorWrapper : IEnumerator<int> { private readonly LinkedList<int>.Enumerator m_Enumerator; public EnumeratorWrapper(LinkedList<int> linkedList) { m_Enumerator = linkedList.GetEnumerator(); } public int Current { get { return m_Enumerator.Current; } } object System.Collections.IEnumerator.Current { get { return Current; } } public bool MoveNext() { return m_Enumerator.MoveNext(); } public void Reset() { ((System.Collections.IEnumerator)m_Enumerator).Reset(); } public void Dispose() { m_Enumerator.Dispose(); } } The key line here is the MoveNext method. When I initially coded this, I thought that the call to m_Enumerator.MoveNext() would alter the enumerator state in the m_Enumerator class variable and so the enumeration would proceed in an orderly fashion through the collection. However, when I ran this code it went into an infinite loop - the m_Enumerator.MoveNext() call wasn't actually changing the state in the m_Enumerator variable at all, and my code was looping forever on the first collection element. It was only after disassembling that method that I found out what was going on The MoveNext method above results in the following IL: .method public hidebysig newslot virtual final instance bool MoveNext() cil managed { .maxstack 1 .locals init ( [0] bool CS$1$0000, [1] valuetype [System]System.Collections.Generic.LinkedList`1/Enumerator CS$0$0001) L_0000: nop L_0001: ldarg.0 L_0002: ldfld valuetype [System]System.Collections.Generic.LinkedList`1/Enumerator EnumeratorWrapper::m_Enumerator L_0007: stloc.1 L_0008: ldloca.s CS$0$0001 L_000a: call instance bool [System]System.Collections.Generic.LinkedList`1/Enumerator::MoveNext() L_000f: stloc.0 L_0010: br.s L_0012 L_0012: ldloc.0 L_0013: ret } Here, the important line is 0002 - m_Enumerator is accessed using the ldfld operator, which does the following: Finds the value of a field in the object whose reference is currently on the evaluation stack. So, what the MoveNext method is doing is the following: public bool MoveNext() { LinkedList<int>.Enumerator CS$0$0001 = this.m_Enumerator; bool CS$1$0000 = CS$0$0001.MoveNext(); return CS$1$0000; } The enumerator instance being modified by the call to MoveNext is the one stored in the CS$0$0001 variable on the stack, and not the one in the EnumeratorWrapper class instance. Hence why the state of m_Enumerator wasn't getting updated. Hmm, ok. Well, why is it doing this? If you have a read of Eric Lippert's blog post about this issue, you'll notice he quotes a few sections of the C# spec. In particular, 7.5.4: ...if the field is readonly and the reference occurs outside an instance constructor of the class in which the field is declared, then the result is a value, namely the value of the field I in the object referenced by E. And my m_Enumerator field is readonly! Indeed, if I remove the readonly from the class variable then the problem goes away, and the code works as expected. The IL confirms this: .method public hidebysig newslot virtual final instance bool MoveNext() cil managed { .maxstack 1 .locals init ( [0] bool CS$1$0000) L_0000: nop L_0001: ldarg.0 L_0002: ldflda valuetype [System]System.Collections.Generic.LinkedList`1/Enumerator EnumeratorWrapper::m_Enumerator L_0007: call instance bool [System]System.Collections.Generic.LinkedList`1/Enumerator::MoveNext() L_000c: stloc.0 L_000d: br.s L_000f L_000f: ldloc.0 L_0010: ret } Notice on line 0002, instead of the ldfld we had before, we've got a ldflda, which does this: Finds the address of a field in the object whose reference is currently on the evaluation stack. Instead of loading the value, we're loading the address of the m_Enumerator field. So now the call to MoveNext modifies the enumerator stored in the class rather than on the stack, and everything works as expected. Previously, I had thought enumerator structs were an odd but interesting feature of the BCL that I had used in the past to do linked list slices. However, effects like this only underline how dangerous mutable structs are, and I'm at a loss to explain why the enumerators were implemented as structs in the first place. (interestingly, the SortedList<TKey, TValue> enumerator is a struct but is private, which makes it even more odd - the only way it can be accessed is as a boxed IEnumerator!). I would love to hear people's theories as to why the enumerators are implemented in such a fashion. And bonus points if you can explain why LinkedList<int>.Enumerator.Reset is an explicit implementation but Dispose is implicit... Note to self: never ever ever code a mutable struct.

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  • Keep taking the tablets

    - by Roger Hart
    A guest editorial for the SimpleTalk newsletter. So why would Red Gate build an Ipad Game? Is it just because tablet devices are exciting and cool? Ok, maybe a little. Mostly, it was seeing that the best existing tablet and smartphone apps do simple, intuitive things, using simple intuitive interfaces to solve single problems. That's pretty close to what we call our own "intuitively simple" approach to software. Tablets and mobile could be fantastic for us, if we can identify those problems that a tablet device can solve. How do you create THE next tool for a completely new technology? We're glad we don't face that problem every day, but it's pretty exciting when we do. We figure we should learn by doing. We created "MobileFoo" (a Red Gate Company) , we picked up some shiny Apple tech, and got to grips with Objective C, and life in the App Store ecosystem. The result so far is an iPad game: Stacks and Heaps It's Rob and Marine's spin on Snakes and Ladders. Instead of snakes we have unhandled exceptions, a blue screen of death, and other hazards. We wanted something compellingly geeky on mobile, and we're pretty sure we've got it. It's trudging through App Store approval as we speak. but if you want to get an idea of what it is like to switch from .net to Objective C, take a look at Rob's post Android and iOS is quite a culture-change for Windows developers. So to give them a feel for the problems real users might have, we needed some real users - we offered our colleagues subsidised tablets. The only conditions were that they get used at work, and we get the feedback. Seeing tablets around the office is starting to give us some data points: Is typing the bottleneck? Will tablets ever cut it as text-entry devices, and could we fix it? Is mobile working held up by the pain of connecting to work LANs? How about security? Multi-tasking will let tablets do more. They're small, easy to use, almost instant to switch on, and connect by Wi Fi. There's plenty on that list to make a sysadmin twitchy. We'll find out as people spend more time working with these devices, and we'd love to hear what you think about tablet devices too. (comments are filtered, what with the spam)

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  • New Wine in New Bottles

    - by Tony Davis
    How many people, when their car shows signs of wear and tear, would consider upgrading the engine and keeping the shell? Even if you're cash-strapped, you'll soon work out the subtlety of the economics, the cost of sudden breakdowns, the precious time lost coping with the hassle, and the low 'book value'. You'll generally buy a new car. The same philosophy should apply to database systems. Mainstream support for SQL Server 2005 ends on April 12; many DBAS, if they haven't done so already, will be considering the migration to SQL Server 2008 R2. Hopefully, that upgrade plan will include a fresh install of the operating system on brand new hardware. SQL Server 2008 R2 and Windows Server 2008 R2 are designed to work together. The improved architecture, processing power, and hyper-threading capabilities of modern processors will dramatically improve the performance of many SQL Server workloads, and allow consolidation opportunities. Of course, there will be many DBAs smiling ruefully at the suggestion of such indulgence. This is nothing like the real world, this halcyon place where hardware and software budgets are limitless, development and testing resources are plentiful, and third party vendors immediately certify their applications for the latest-and-greatest platform! As with cars, or any other technology, the justification for a complete upgrade is complex. With Servers, the extra cost at time of upgrade will generally pay you back in terms of the increased performance of your business applications, reduced maintenance costs, training costs and downtime. Also, if you plan and design carefully, it's possible to offset hardware costs with reduced SQL Server licence costs. In his forthcoming SQL Server Hardware book, Glenn Berry describes a recent case where he was able to replace 4 single-socket database servers with one two-socket server, saving about $90K in hardware costs and $350K in SQL Server license costs. Of course, there are exceptions. If you do have a stable, reliable, secure SQL Server 6.5 system that still admirably meets the needs of a specific business requirement, and has no security vulnerabilities, then by all means leave it alone. Why upgrade just for the sake of it? However, as soon as a system shows sign of being unfit for purpose, or is moving out of mainstream support, the ruthless DBA will make the strongest possible case for a belts-and-braces upgrade. We'd love to hear what you think. What does your typical upgrade path look like? What are the major obstacles? Cheers, Tony.

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  • Hype and LINQ

    - by Tony Davis
    "Tired of querying in antiquated SQL?" I blinked in astonishment when I saw this headline on the LinqPad site. Warming to its theme, the site suggests that what we need is to "kiss goodbye to SSMS", and instead use LINQ, a modern query language! Elsewhere, there is an article entitled "Why LINQ beats SQL". The designers of LINQ, along with many DBAs, would, I'm sure, cringe with embarrassment at the suggestion that LINQ and SQL are, in any sense, competitive ways of doing the same thing. In fact what LINQ really is, at last, is an efficient, declarative language for C# and VB programmers to access or manipulate data in objects, local data stores, ORMs, web services, data repositories, and, yes, even relational databases. The fact is that LINQ is essentially declarative programming in a .NET language, and so in many ways encourages developers into a "SQL-like" mindset, even though they are not directly writing SQL. In place of imperative logic and loops, it uses various expressions, operators and declarative logic to build up an "expression tree" describing only what data is required, not the operations to be performed to get it. This expression tree is then parsed by the language compiler, and the result, when used against a relational database, is a SQL string that, while perhaps not always perfect, is often correctly parameterized and certainly no less "optimal" than what is achieved when a developer applies blunt, imperative logic to the SQL language. From a developer standpoint, it is a mistake to consider LINQ simply as a substitute means of querying SQL Server. The strength of LINQ is that that can be used to access any data source, for which a LINQ provider exists. Microsoft supplies built-in providers to access not just SQL Server, but also XML documents, .NET objects, ADO.NET datasets, and Entity Framework elements. LINQ-to-Objects is particularly interesting in that it allows a declarative means to access and manipulate arrays, collections and so on. Furthermore, as Michael Sorens points out in his excellent article on LINQ, there a whole host of third-party LINQ providers, that offers a simple way to get at data in Excel, Google, Flickr and much more, without having to learn a new interface or language. Of course, the need to be generic enough to deal with a range of data sources, from something as mundane as a text file to as esoteric as a relational database, means that LINQ is a compromise and so has inherent limitations. However, it is a powerful and beautifully compact language and one that, at least in its "query syntax" guise, is accessible to developers and DBAs alike. Perhaps there is still hope that LINQ can fulfill Phil Factor's lobster-induced fantasy of a language that will allow us to "treat all data objects, whether Word files, Excel files, XML, relational databases, text files, HTML files, registry files, LDAPs, Outlook and so on, in the same logical way, as linked databases, and extract the metadata, create the entities and relationships in the same way, and use the same SQL syntax to interrogate, create, read, write and update them." Cheers, Tony.

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  • Automated Error Reporting in .NET Reflector - harnessing the most powerful test rig in existence

    - by Alex.Davies
    I know a testing system that will find more bugs than all the unit testing, integration testing, and QA you could possibly do. And the chances are you're not using it. It's called your users. It's a cliché that you should test so that you find your bugs rather than your users. Of course you should. But it's also a cliché that no software is ever shipped bug-free. Lost cause? No, opportunity! I think .NET Reflector 6 is pretty stable. In fact I know exactly how stable it is, because some (surprisingly high) proportion of its users tell me every time it crashes: If they press "Send Error Report", I get: And then I fix it. As a rough guess, while a standard stack trace is enough to fix a problem 30% of the time, having all those local variables in the stack trace means I can fix it about 80% of the time. How does this all happen? Did it take ages to code this swish system? Nope, it was one checkbox in SmartAssembly. It adds some clever code to your assembly to capture local variables every time an exception is thrown, and to ask your user to report it to you, with a variety of other useful information. Of course not all bugs show up as exceptions. But if you get used to knowing that SmartAssembly will tell you when an exception happens, you begin to change your coding style. Now, as long as an exception gets thrown in any situation you don't expect, you'll fix it if it ever happens. You'll start throwing exceptions liberally, and stop having to think about whether tiny edge cases are possible, as long as they throw an exception if they happen.

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  • Implementing User-Defined Hierarchies in SQL Server Analysis Services

    To be able to drill into multidimensional cube data at several levels, you must implement all of the hierarchies on the database dimensions. Then you'll create the attribute relationships necessary to optimize performance. Analysis Services hierarchies offer plenty of possibilities for displaying the data that your business requires. Rob Sheldon continues his series on SQL Server Analysis Services 2008.

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  • Showplan Operator of the Week - Compute Scalar

    The third part of Fabiano's mission to describe the major Showplan Operators used by SQL Server's Query Optimiser continues with the 'Compute Scalar' operator. Fabiano shows how a tweak to SQL to avoid a 'Compute Scalar' step can improve its performance.

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  • Overload Avoidance

    - by mikef
    A little under a year ago, Matt Simmons wrote a rather reflective article about his terrifying brush with stress-induced ill health. SysAdmins and DBAs have always been prime victims of work-related stress, but I wonder if that predilection is perhaps getting worse, despite the best efforts of Matt and his trusty side-kick, HR. The constant pressure from share-holders and CFOs to 'streamline' the workforce is partially to blame, but the more recent culprit is technology itself. I can't deny that the rise of technologies like virtualization, PowerCLI, PowerShell, and a host of others has been a tremendous boon. As a result, individual IT professionals are now able to handle more and more tasks and manage increasingly large and complex environments. But, without a doubt, this is a two-edged sword; The reward for competence is invariably more work. Unfortunately, SysAdmins play such a pivotal role in modern business that it's easy to see how they can very quickly become swamped in conflicting demands coming from different directions. However, that doesn't justify the ridiculous hours many are asked (or volunteer) to devote to their work. Admirably though their commitment is, it isn't healthy for them, it sets a dangerous expectation, and eventually something will snap. There are times when everyone needs to step up to the plate outside of 'normal' work hours, but that time isn't all the time. Naturally, with all that lovely technology, you can automate more and more of those tricky tasks to keep on top of the workload, but you are still only human. Clever though you may be, there is a very real limit to how far technology can take you. I'm not suggesting that you avoid these technologies, or deliberately aim for mediocrity; I'm just saying that you need to be more than just technically skilled (and Wesley Nonapeptide riffs on and around this topic in his excellent 'Telepathic Robot Drones' blog post). You need to be able to manage expectations, not just Exchange. Specifically, that means your own expectations of what you are capable of, because those come before everyone else's. After all, how can you keep your work-life balance under control, if you're the one setting the bar way too high? Talking to your manager, or discussing issues with your users, is only going to be productive if you have some facts to work with. "Know Thyself" is the first law of managing work overload, and this is obviously a skill which people develop over time; the fact that veteran Sysadmins exist at all is testament to this. I'd just love to know how you get to that point. Personally, I'm using RescueTime to keep myself honest, but I'm open to recommendations for better methods. Do you track your own time, do you have an intuitive sense of what is possible, or do you just rely on someone else to handle that all for you? Cheers, Michael

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  • The SmartAssembly Rearchitecture

    - by Simon Cooper
    You may have noticed that not a lot has happened to SmartAssembly in the past few months. However, the team has been very busy behind the scenes working on an entirely new version of SmartAssembly. SmartAssembly 6.5 Over the past few releases of SmartAssembly, the team had come to the realisation that the current 'architecture' - grown organically, way before RedGate bought it, from a simple name obfuscator over the years into a full-featured obfuscator and assembly instrumentation tool - was simply not up to the task. Not for what we wanted to do with it at the time, and not what we have planned for the future. Not only was it not up to what we wanted it to do, but it was severely limiting our development capabilities; long-standing bugs in the root architecture that couldn't be fixed, some rather...interesting...design decisions, and convoluted logic that increased the complexity of any bugfix or new feature tenfold. So, we set out to fix this. Earlier this year, a new engine was written on which SmartAssembly would be based. Over the following few months, each feature was ported over to the new engine and extensively tested by our existing unit and integration tests. The engine was linked into the existing UI (no easy task, due to the tight coupling between the UI and old engine), and existing RedGate products were tested on the new SmartAssembly to ensure the new engine acted in the same way. The result is SmartAssembly 6.5. The risks of a rearchitecture Are there risks to rearchitecting a product like SmartAssembly? Of course. There was a lot of undocumented behaviour in the old engine, and as part of the rearchitecture we had to find this behaviour, define it, and document it. In the process we found some behaviour of the old engine that simply did not make sense; hence the changes in pruning & obfuscation behaviour in the release notes. All the special edge cases we had to find, document, and re-implement. There was a chance that these special cases would not be found until near the end of the project, when everything is functionally complete and interacting together. By that stage, it would be hard to go back and change anything without a whole lot of extra work, delaying the release by months. We always knew this was a possibility; our initial estimate of the time required was '4 months, ± 4 months'. And that was including various mitigation strategies to reduce the likelihood of these issues being found right at the end. Fortunately, this worst-case did not happen. However, the rearchitecture did produce some benefits. As well as numerous bug fixes that we could not fix any other way, we've also added logging that lets you find out exactly why a particular field or property wasn't pruned or obfuscated. There's a new command line interface, we've tested it with WP7.1 and Silverlight 5, and we've added a new option to error reporting to improve the performance of instrumented apps by ~10%, at the cost of inaccurate line numbers in reports. So? What differences will I see? Largely none. SmartAssembly 6.5 produces the same output as SmartAssembly 6.2. The performance of 6.5 will be much faster for some users, and generally the same as 6.2 for the remaining. If you've encountered a bug with previous versions of SmartAssembly, I encourage you to try 6.5, as it has most likely been fixed in the rearchitecture. If you encounter a bug with 6.5, please do tell us; we'll be doing another release quite soon, so we'll aim to fix any issues caused by 6.5 in that release. Most importantly, the new architecture finally allows us to implement some Big Things with SmartAssembly we've been planning for many months; these will fundamentally change how you build, release and monitor your application. Stay tuned for further updates!

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  • A Community Cure for a String Splitting Headache

    - by Tony Davis
    A heartwarming tale of dogged perseverance and Community collaboration to solve some SQL Server string-related headaches. Michael J Swart posted a blog this week that had me smiling in recognition and agreement, describing how an inquisitive Developer or DBA deals with a problem. It's a three-step process, starting with discomfort and anxiety; a feeling that one doesn't know as much about one's chosen specialized subject as previously thought. It progresses through a phase of intense research and learning until finally one achieves breakthrough, blessed relief and renewed optimism. In this case, the discomfort was provoked by the mystery of massively high CPU when searching Unicode strings in SQL Server. Michael explored the problem via Stack Overflow, Google and Twitter #sqlhelp, finally leading to resolution and a blog post that shared what he learned. Perfect; except that sometimes you have to be prepared to share what you've learned so far, while still mired in the phase of nagging discomfort. A good recent example of this recently can be found on our own blogs. Despite being a loud advocate of the lightning fast T-SQL-based string splitting techniques, honed to near perfection over many years by Jeff Moden and others, Phil Factor retained a dogged conviction that, in theory, shredding element-based XML using XQuery ought to be even more efficient for splitting a string to create a table. After some careful testing, he found instead that the XML way performed and scaled miserably by comparison. Somewhat subdued, and with a nagging feeling that perhaps he was still missing "something", he posted his findings. What happened next was a joy to behold; the community jumped in to suggest subtle changes in approach, using an attribute-based rather than element-based XML list, and tweaking the XQuery shredding. The result was performance and scalability that surpassed all other techniques. I asked Phil how quickly he would have arrived at the real breakthrough on his own. His candid answer was "never". Both are great examples of the power of Community learning and the latter in particular the importance of being brave enough to parade one's ignorance. Perhaps Jeff Moden will accept the string-splitting gauntlet one more time. To quote the great man: you've just got to love this community! If you've an interesting tale to tell about being helped to a significant breakthrough for a problem by the community, I'd love to hear about it. Cheers, Tony.

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  • Automated Error Reporting = More Robust Software

    - by Laila
    I would like to tell you how to revolutionize your software development process </marketing hyperbole> On a more serious note, we (Red Gate's .NET Development team) recently rolled a new tool into our development process which has made our lives dramatically easier AND improved the quality of our software, and I (& one of our developers, Alex Davies) just wanted to take a quick moment to share the love. I work with a development team that takes pride in what they ship, so we take software testing rather seriously. For every development project we run, we allocate at least one software tester for every two developers, and we never ship software without first shipping early access releases and betas to get user feedback. And therein lies the challenge -encouraging users to provide consistent, useful feedback is a headache, but without that feedback, improving the software is. tricky. Until fairly recently, we used the standard (if long-winded) approach of receiving bug reports of variable quality via email or through our support forums. If that didn't give us enough information to reproduce the problem - which was most of the time - we had to enter into a time-consuming to-and-fro conversation with the end-user, to get scrape together the data we needed to work out where the problem lay. As I'm sure you're aware, this is painfully slow. To the delight of the team, we recently got to work with SmartAssembly, which lets us embed automated exception and error reporting into our software with very little pain, and we decided to do a little dogfooding. As a result, we've have made a really handy (if perhaps slightly obvious) discovery: As soon as we release a beta, or indeed any release of software, we now get tonnes of customer feedback through automated error reports. Making this process easier for our users has dramatically increased the amount (and quality) of feedback we get. From their point of view, they get an experience similar to Microsoft's error reporting, and process is essentially idiot-proof. From our side of things, we can now react much faster to the information we get, fixing the bugs and shipping a new-and-improved release, which our users rather appreciate. Smiles and hugs all round. Even more so because, as we're use SmartAssembly's Automated Error Reporting, we get to avoid having to spend weeks building an exception reporting mechanism. It takes just a few minutes to add reporting to a project, and we get a bunch of useful information back, like a stack trace and the values of all the local variables, which we can use to fix bugs. Happily, "Automated Error Reporting = More Robust Software" can actually be read two ways: we've found that we not only ship higher quality software, but we also release within a shorter time. We can ship stable software that our users are happy to upgrade to, and we then bask in the glory of lots of positive customer feedback. Once we'd starting working with SmartAssembly, we were curious to know how widespread error reporting was as a practice. Our product manager ran a survey in autumn last year, and found that 40% of software developers never really considered deploying error reporting. Considering how we've now got plenty of experience on the subject, one of our dev guys, Alex Davies, thought we should share what we've learnt, and he's kindly offered to host a webinar on delivering robust software with Automated Error Reporting. Drawing on our own in-house development experiences, he'll cover how to add error reporting to your program, how to actually use the error reports to fix bugs (don't snigger, not everyone's as bright as you), how to customize the error report dialog that your users see, and how to automatically get log files from your users' machine. The webinar will take place on Jan 25th (that's next week). It's free to attend, but you'll still need to register to hear Alex's dulcet tones.

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  • SQL Server CTE Basics

    The CTE was introduced into standard SQL in order to simplify various classes of SQL Queries for which a derived table just wasn't suitable. For some reason, it can be difficult to grasp the techniques of using it. Well, that's before Rob Sheldon explained it all so clearly for us.

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  • Regional Office Virtualization - Less Can Be More

    The dream of an 'office in a box' has been around for years, but the increasing sophistication of virtualization software has turned the dream into reality. Ben Lye explains the problems and benefits of reducing the amount of physical hardware that were deployed in his organisation's regional offices.

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  • Alan Turing Needs Your Help

    - by Chris Massey
    Well. sort of. Clearly, you are using a computer. If you are on this site, you are probably quite familiar with computers as artifacts of our modern society. Hopefully, you are also familiar with the fact that Alan Turing, logician and mathematician extraordinaire, was instrumental in laying down the foundations of modern computer science, and did a little work to help turn the tide of WWII in the Allies' favor. Hold that thought. A phenomenal collection of Turing's papers (including his first ever...(read more)

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  • Access Denied

    - by Tony Davis
    When Microsoft executives wake up in the night screaming, I suspect they are having a nightmare about their own version of Frankenstein's monster. Created with the best of intentions, without thinking too hard of the long-term strategy, and having long outlived its usefulness, the monster still lives on, occasionally wreaking vengeance on the innocent. Its name is Access; a living synthesis of disparate body parts that is resistant to all attempts at a mercy-killing. In 1986, Microsoft had no database products, and needed one for their new OS/2 operating system, the successor to MSDOS. In 1986, they bought exclusive rights to Sybase DataServer, and were also intent on developing a desktop database to capture Ashton-Tate's dominance of that market, with dbase. This project, first called 'Omega' and later 'Cirrus', eventually spawned two products: Visual Basic in 1991 and Access in late 1992. Whereas Visual Basic battled with PowerBuilder for dominance in the client-server market, Access easily won the desktop database battle, with Dbase III and DataEase falling away. Access did an excellent job of abstracting and simplifying the task of building small database applications in a short amount of time, for a small number of departmental users, and often for a transient requirement. There is an excellent front end and forms generator. We not only see it in Access but parts of it also reappear in SSMS. It's good. A business user can pull together useful reports, without relying on extensive technical support. A skilled Access programmer can deliver a fairly sophisticated application, whilst the traditional client-server programmer is still sharpening his pencil. Even for the SQL Server programmer, the forms generator of Access is useful for sketching out application designs. So far, so good, but here's where the problems start; Access ties together two different products and the backend of Access is the bugbear. The limitations of Jet/ACE are well-known and documented. They range from MDB files that are prone to corruption, especially as they grow in size, pathetic security, and "copy and paste" Backups. The biggest problem though, was an infamous lack of scalability. Because Microsoft never realized how long the product would last, they put little energy into improving the beast. Microsoft 'ate their own dog food' by using Access for Microsoft Exchange and Outlook. They choked on it. For years, scalability and performance problems with Exchange Server have been laid at the door of the Jet Blue engine on which it relies. Substantial development work in Exchange 2010 was required, just in order to improve the engine and storage schema so that it more efficiently handled the reading and writing of mails. The alternative of using SQL Server just never panned out. The Jet engine was designed to limit concurrent users to a small number (10-20). When Access applications outgrew this, bitter experience proved that there really is no easy upgrade path from Access to SQL Server, beyond rewriting the whole lot from scratch. The various initiatives to do this never quite bridged the cultural gulf between Access and a true relational database So, what are the obvious alternatives for small, strategic database applications? I know many users who, for simple 'list maintenance' requirements are very happy using Excel databases. Surely, now that PowerPivot has led the way, it is time for Microsoft to offer a new RAD package for database application development; namely an Excel-based front end for SQL Server Express. In that way, we'll have a powerful and familiar front end, to a scalable database, and a clear upgrade path when an app takes off and needs to go enterprise. Cheers, Tony.

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  • .Net Reflector 6.5 EAP now available

    - by CliveT
    With the release of CLR 4 being so close, we’ve been working hard on getting the new C# and VB language features implemented inside Reflector. The work isn’t complete yet, but we have some of the features working. Most importantly, there are going to be changes to the Reflector object model, and we though it would be useful for people to see the changes and have an opportunity to comment on them. Before going any further, we should tell you what the EAP contains that’s different from the released version. A number of bugs have been fixed, mainly bugs that were raised via the forum. This is slightly offset by the fact that this EAP hasn’t had a whole lot of testing and there may have been new bugs introduced during the development work we’ve been doing. The C# language writer has been changed to display in and out co- and contra-variance markers on interfaces and delegates, and to display default values for optional parameters in method definitions. We also concisely display values passed by reference into COM calls. However, we do not change callsites to display calls using named parameters; this looks like hard work to get right. The forthcoming version of the C# language introduces dynamic types and dynamic calls. The new version of Reflector should display a dynamic call rather than the generated C#: dynamic target = MyTestObject(); target.Hello("Mum"); We have a few bugs in this area where we are not casting to dynamic when necessary. These have been fixed on a branch and should make their way into the next EAP. To support the dynamic features, we’ve added the types IDynamicMethodReferenceExpression, IDynamicPropertyIndexerExpression, and IDynamicPropertyReferenceExpression to the object model. These types, based on the versions without “Dynamic” in the name, reflect the fact that we don’t have full information about the method that is going to be called, but only have its name (as a string). These interfaces are going to change – in an internal version, they have been extended to include information about which parameter positions use runtime types and which use compile time types. There’s also the interface, IDynamicVariableDeclaration, that can be used to determine if a particular variable is used at dynamic call sites as a target. A couple of these language changes have also been added to the Visual Basic language writer. The new features are exposed only when the optimization level is set to .NET 4. When the level is set this high, the other standard language writers will simply display a message to say that they do not handle such an optimization level. Reflector Pro now has 4.0 as an optional compilation target and we have done some work to get the pdb generation right for these new features. The EAP version of Reflector no longer installs the add-in on startup. The first time you run the EAP, it displays the integration options dialog. You can use the checkboxes to select the versions of Visual Studio into which you want to install the EAP version. Note that you can only have one version of Reflector Pro installed in Visual Studio; if you install into a Visual Studio that has another version installed, the previous version will be removed. Please try it out and send your feedback to the EAP forum.

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  • Adding Actions to a Cube in SQL Server Analysis Services 2008

    Actions are powerful way of extending the value of SSAS cubes for the end user. They can click on a cube or portion of a cube to start an application with the selected item as a parameter, or to retrieve information about the selected item. Actions haven't been well-documented until now; Robert Sheldon once more makes everything clear.

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  • Subterranean IL: Compiling C# exception handlers

    - by Simon Cooper
    An exception handler in C# combines the IL catch and finally exception handling clauses into a single try statement: try { Console.WriteLine("Try block") // ... } catch (IOException) { Console.WriteLine("IOException catch") // ... } catch (Exception e) { Console.WriteLine("Exception catch") // ... } finally { Console.WriteLine("Finally block") // ... } How does this get compiled into IL? Initial implementation If you remember from my earlier post, finally clauses must be specified with their own .try clause. So, for the initial implementation, we take the try/catch/finally, and simply split it up into two .try clauses (I have to use label syntax for this): StartTry: ldstr "Try block" call void [mscorlib]System.Console::WriteLine(string) // ... leave.s End EndTry: StartIOECatch: ldstr "IOException catch" call void [mscorlib]System.Console::WriteLine(string) // ... leave.s End EndIOECatch: StartECatch: ldstr "Exception catch" call void [mscorlib]System.Console::WriteLine(string) // ... leave.s End EndECatch: StartFinally: ldstr "Finally block" call void [mscorlib]System.Console::WriteLine(string) // ... endfinally EndFinally: End: // ... .try StartTry to EndTry catch [mscorlib]System.IO.IOException handler StartIOECatch to EndIOECatch catch [mscorlib]System.Exception handler StartECatch to EndECatch .try StartTry to EndTry finally handler StartFinally to EndFinally However, the resulting program isn't verifiable, and doesn't run: [IL]: Error: Shared try has finally or fault handler. Nested try blocks What's with the verification error? Well, it's a condition of IL verification that all exception handling regions (try, catch, filter, finally, fault) of a single .try clause have to be completely contained within any outer exception region, and they can't overlap with any other exception handling clause. In other words, IL exception handling clauses must to be representable in the scoped syntax, and in this example, we're overlapping catch and finally clauses. Not only is this example not verifiable, it isn't semantically correct. The finally handler is specified round the .try. What happens if you were able to run this code, and an exception was thrown? Program execution enters top of try block, and exception is thrown within it CLR searches for an exception handler, finds catch Because control flow is leaving .try, finally block is run The catch block is run leave.s End inside the catch handler branches to End label. We're actually running the finally before the catch! What we do about it What we actually need to do is put the catch clauses inside the finally clause, as this will ensure the finally gets executed at the correct time (this time using scoped syntax): .try { .try { ldstr "Try block" call void [mscorlib]System.Console::WriteLine(string) // ... leave.s End } catch [mscorlib]System.IO.IOException { ldstr "IOException catch" call void [mscorlib]System.Console::WriteLine(string) // ... leave.s End } catch [mscorlib]System.Exception { ldstr "Exception catch" call void [mscorlib]System.Console::WriteLine(string) // ... leave.s End } } finally { ldstr "Finally block" call void [mscorlib]System.Console::WriteLine(string) // ... endfinally } End: ret Returning from methods There is a further semantic mismatch that the C# compiler has to deal with; in C#, you are allowed to return from within an exception handling block: public int HandleMethod() { try { // ... return 0; } catch (Exception) { // ... return -1; } } However, you can't ret inside an exception handling block in IL. So the C# compiler does a leave.s to a ret outside the exception handling area, loading/storing any return value to a local variable along the way (as leave.s clears the stack): .method public instance int32 HandleMethod() { .locals init ( int32 retVal ) .try { // ... ldc.i4.0 stloc.0 leave.s End } catch [mscorlib]System.Exception { // ... ldc.i4.m1 stloc.0 leave.s End } End: ldloc.0 ret } Conclusion As you can see, the C# compiler has quite a few hoops to jump through to translate C# code into semantically-correct IL, and hides the numerous conditions on IL exception handling blocks from the C# programmer. Next up: catch-all blocks, and how the runtime deals with non-Exception exceptions.

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  • ANTS Performance Profiler 7.0 has been released!

    - by Michaela Murray
    Please join me in welcoming ANTS Performance Profiler 7 to the world of .NET. ANTS Performance Profiler is a .NET code profiling tool. It lets you identify performance bottlenecks within minutes and therefore enables you to optimize your application performance. Version 7.0 includes integrated decompilation: when profiling methods and assemblies with no source code file, you can generate source code right from the profiler interface. You can then browse and navigate this automatically generated source as if it was your own. If you have an assembly's PDB file but no source, integrated decompilation even lets you view line-level timings for each method, pinpointing the exact cause of performance bottlenecks. Integrated decompilation is powered by .NET Reflector, but you don't need Reflector installed to use the functionality. Watch this video to see it in action. Also new in ANTS Performance Profiler 7.0: · Full support for SharePoint 2010 - No need to manually configure profiling for the latest version of SharePoint · Full support for IIS Express · Azure and Amazon EC2 support, enabling you to profile in the cloud Please click here, for more details about the ANTS Performance Profiler 7.0.

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  • From WinForm to WPF: A Quick Reference Guide

    Michael Sorens provides a handy wallchart to help migration between WinForm / WPF, VS 2008 / 2010, and .NET 3.5 / 4.0. this can be downloaded for free from the speech-bubble at the head of the article. He also describes the current weaknesses in WPF, and the most obvious differences between the two.

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  • Reflector Pro has now been released!

    - by CliveT
    After moving into the .NET division in May , and having a great time working on Reflector, I'm pleased to say that the results of that work are now available. Reflector Pro has now been released! The old Reflector as you know and love it is still available free of charge, and as part of this project we've fixed a number of bugs in the de-compilation that have been around for a long time. The Pro version comes as an add-in for Visual Studio - this offers dynamic de-compilation and generation of pdb files which allow you to step into the de-compiled code. Alex has some good pictures of this functionality on his beta post from around a month ago. Thanks to the other guys who've worked on this for taking me along for the ride - Alex, Andrew, Bart and Jason. Stephen did some great usability work, Chris Alford did some great technical authoring and Laila handled the launch publicity. Like all projects, there's always more I'd like to have done, but what we have looks like a pretty powerful addition to the developer's set of tools to me. Please try it and give us feedback on the forum.

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  • Sharing configuration settings between Windows Azure roles

    - by theo.spears
    If you are working on a medium-large Windows Azure project it's likely it will involve more than one role, for example separate web and worker roles. Unfortunately although all the windows azure configuration settings are stored in a single cscfg file, there is no way to share configuration settings between multiple roles. This means you have to duplicate common settings like connection strings across all your roles. There is an open Connect issue about this topic, but Microsoft have not said when they will fix it. In the mean time I've put together a dirty dirty hack cunning workaround that creates a fake role containing your shared configuration settings, and copies it to all roles as part of the build process. Here's how you set it up: 1. Download the zip file attached to this post, and unzip it into the folder containing your Azure project (not your solution folder). 2. Edit your csdef and cscfg files to include the placeholder project ServiceDefinition.csdef<?xml version="1.0" encoding="utf-8"?> <ServiceDefinition name="AzureSpendNotifier" http://schemas.microsoft.com/ServiceHosting/2008/10/ServiceDefinition%22"http://schemas.microsoft.com/ServiceHosting/2008/10/ServiceDefinition"> <WorkerRole name="GLOBAL"> <ConfigurationSettings> <Setting name="ExampleSetting" /> </ConfigurationSettings> </WorkerRole> <WorkerRole name="MyWorker"> <ConfigurationSettings> </ConfigurationSettings> </WorkerRole> <WebRole name="MyWeb"> <Sites> <Site name="Web"> <Bindings> <Binding name="WebEndpoint" endpointName="WebEndpoint" /> </Bindings> </Site> </Sites> <ConfigurationSettings> </ConfigurationSettings> </WebRole> </ServiceDefinition> ServiceConfiguration.cscfg<?xml version="1.0" encoding="utf-8"?> <ServiceConfiguration serviceName="AzureSpendNotifier" xmlns=http://schemas.microsoft.com/ServiceHosting/2008/10/ServiceConfiguration osFamily="1" osVersion="*"> <Role name="GLOBAL"> <ConfigurationSettings> <Setting name="ExampleSetting" value="Hello World" /> </ConfigurationSettings> <Instances count="1" /> </Role> <Role name="MyWorker"> <Instances count="1" /> <ConfigurationSettings> </ConfigurationSettings> </Role> <Role name="MyWeb"> <Instances count="1" /> <ConfigurationSettings> </ConfigurationSettings> </Role> </ServiceConfiguration> It is important that all your roles contain a ConfigurationSettings entry in both cscfg and csdef files, even if it's empty- otherwise the shared configuration settings will not be inserted. 3. Open your azure deployment (.ccproj) project in notepad, and add the highlighted line below: ... <Import Project="$(CloudExtensionsDir)Microsoft.CloudService.targets" /> <Import Project="globalsettings/globalsettings.targets" /> </Project> It is important you add this below the Microsoft.CloudService.targets import line, as it replaces some of the rules defined in that file. Visual studio will prompt you to reload the project, say yes. At this point you will have a new Azure role called 'GLOBAL' with settings you can edit through the visual studio properties panel as normal. This role will never be deployed, but any settings you add to it will be copied to all your other roles when deployed or tested locally within visual studio.

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  • Converting Encrypted Values

    - by Johnm
    Your database has been protecting sensitive data at rest using the cell-level encryption features of SQL Server for quite sometime. The employees in the auditing department have been inviting you to their after-work gatherings and buying you drinks. Thousands of customers implicitly include you in their prayers of thanks giving as their identities remain safe in your company's database. The cipher text resting snuggly in a column of the varbinary data type is great for security; but it can create some interesting challenges when interacting with other data types such as the XML data type. The XML data type is one that is often used as a message type for the Service Broker feature of SQL Server. It also can be an interesting data type to capture for auditing or integrating with external systems. The challenge that cipher text presents is that the need for decryption remains even after it has experienced its XML metamorphosis. Quite an interesting challenge nonetheless; but fear not. There is a solution. To simulate this scenario, we first will want to create a plain text value for us to encrypt. We will do this by creating a variable to store our plain text value: -- set plain text value DECLARE @PlainText NVARCHAR(255); SET @PlainText = 'This is plain text to encrypt'; The next step will be to create a variable that will store the cipher text that is generated from the encryption process. We will populate this variable by using a pre-defined symmetric key and certificate combination: -- encrypt plain text value DECLARE @CipherText VARBINARY(MAX); OPEN SYMMETRIC KEY SymKey     DECRYPTION BY CERTIFICATE SymCert     WITH PASSWORD='mypassword2010';     SET @CipherText = EncryptByKey                          (                            Key_GUID('SymKey'),                            @PlainText                           ); CLOSE ALL SYMMETRIC KEYS; The value of our newly generated cipher text is 0x006E12933CBFB0469F79ABCC79A583--. This will be important as we reference our cipher text later in this post. Our final step in preparing our scenario is to create a table variable to simulate the existence of a table that contains a column used to hold encrypted values. Once this table variable has been created, populate the table variable with the newly generated cipher text: -- capture value in table variable DECLARE @tbl TABLE (EncVal varbinary(MAX)); INSERT INTO @tbl (EncVal) VALUES (@CipherText); We are now ready to experience the challenge of capturing our encrypted column in an XML data type using the FOR XML clause: -- capture set in xml DECLARE @xml XML; SET @xml = (SELECT               EncVal             FROM @tbl AS MYTABLE             FOR XML AUTO, BINARY BASE64, ROOT('root')); If you add the SELECT @XML statement at the end of this portion of the code you will see the contents of the XML data in its raw format: <root>   <MYTABLE EncVal="AG4Skzy/sEafeavMeaWDBwEAAACE--" /> </root> Strangely, the value that is captured appears nothing like the value that was created through the encryption process. The result being that when this XML is converted into a readable data set the encrypted value will not be able to be decrypted, even with access to the symmetric key and certificate used to perform the decryption. An immediate thought might be to convert the varbinary data type to either a varchar or nvarchar before creating the XML data. This approach makes good sense. The code for this might look something like the following: -- capture set in xml DECLARE @xml XML; SET @xml = (SELECT              CONVERT(NVARCHAR(MAX),EncVal) AS EncVal             FROM @tbl AS MYTABLE             FOR XML AUTO, BINARY BASE64, ROOT('root')); However, this results in the following error: Msg 9420, Level 16, State 1, Line 26 XML parsing: line 1, character 37, illegal xml character A quick query that returns CONVERT(NVARCHAR(MAX),EncVal) reveals that the value that is causing the error looks like something off of a genuine Chinese menu. While this situation does present us with one of those spine-tingling, expletive-generating challenges, rest assured that this approach is on the right track. With the addition of the "style" argument to the CONVERT method, our solution is at hand. When dealing with converting varbinary data types we have three styles available to us: - The first is to not include the style parameter, or use the value of "0". As we see, this style will not work for us. - The second option is to use the value of "1" will keep our varbinary value including the "0x" prefix. In our case, the value will be 0x006E12933CBFB0469F79ABCC79A583-- - The third option is to use the value of "2" which will chop the "0x" prefix off of our varbinary value. In our case, the value will be 006E12933CBFB0469F79ABCC79A583-- Since we will want to convert this back to varbinary when reading this value from the XML data we will want the "0x" prefix, so we will want to change our code as follows: -- capture set in xml DECLARE @xml XML; SET @xml = (SELECT              CONVERT(NVARCHAR(MAX),EncVal,1) AS EncVal             FROM @tbl AS MYTABLE             FOR XML AUTO, BINARY BASE64, ROOT('root')); Once again, with the inclusion of the SELECT @XML statement at the end of this portion of the code you will see the contents of the XML data in its raw format: <root>   <MYTABLE EncVal="0x006E12933CBFB0469F79ABCC79A583--" /> </root> Nice! We are now cooking with gas. To continue our scenario, we will want to parse the XML data into a data set so that we can glean our freshly captured cipher text. Once we have our cipher text snagged we will capture it into a variable so that it can be used during decryption: -- read back xml DECLARE @hdoc INT; DECLARE @EncVal NVARCHAR(MAX); EXEC sp_xml_preparedocument @hDoc OUTPUT, @xml; SELECT @EncVal = EncVal FROM OPENXML (@hdoc, '/root/MYTABLE') WITH ([EncVal] VARBINARY(MAX) '@EncVal'); EXEC sp_xml_removedocument @hDoc; Finally, the decryption of our cipher text using the DECRYPTBYKEYAUTOCERT method and the certificate utilized to perform the encryption earlier in our exercise: SELECT     CONVERT(NVARCHAR(MAX),                     DecryptByKeyAutoCert                          (                            CERT_ID('AuditLogCert'),                            N'mypassword2010',                            @EncVal                           )                     ) EncVal; Ah yes, another hurdle presents itself! The decryption produced the value of NULL which in cryptography means that either you don't have permissions to decrypt the cipher text or something went wrong during the decryption process (ok, sometimes the value is actually NULL; but not in this case). As we see, the @EncVal variable is an nvarchar data type. The third parameter of the DECRYPTBYKEYAUTOCERT method requires a varbinary value. Therefore we will need to utilize our handy-dandy CONVERT method: SELECT     CONVERT(NVARCHAR(MAX),                     DecryptByKeyAutoCert                          (                             CERT_ID('AuditLogCert'),                             N'mypassword2010',                             CONVERT(VARBINARY(MAX),@EncVal)                           )                     ) EncVal; Oh, almost. The result remains NULL despite our conversion to the varbinary data type. This is due to the creation of an varbinary value that does not reflect the actual value of our @EncVal variable; but rather a varbinary conversion of the variable itself. In this case, something like 0x3000780030003000360045003--. Considering the "style" parameter got us past XML challenge, we will want to consider its power for this challenge as well. Knowing that the value of "1" will provide us with the actual value including the "0x", we will opt to utilize that value in this case: SELECT     CONVERT(NVARCHAR(MAX),                     DecryptByKeyAutoCert                          (                            CERT_ID('SymCert'),                            N'mypassword2010',                            CONVERT(VARBINARY(MAX),@EncVal,1)                           )                     ) EncVal; Bingo, we have success! We have discovered what happens with varbinary data when captured as XML data. We have figured out how to make this data useful post-XML-ification. Best of all we now have a choice in after-work parties now that our very happy client who depends on our XML based interface invites us for dinner in celebration. All thanks to the effective use of the style parameter.

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  • Modifying Contiguous Time Periods in a History Table

    Alex Kuznetsov is credited with a clever technique for creating a history table for SQL that is designed to store contiguous time periods and check that these time periods really are contiguous, using nothing but constraints. This is now increasingly useful with the DATE data type in SQL Server. The modification of data in this type of table isn't always entirely intuitive so Alex is on hand to give a brief explanation of how to do it.

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