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  • Create setenv.sh to set system property

    - by user3475398
    I have to use setenv.sh to set system properties. I am using Linux OS and Tomcat Server 6. As described here Linux Environment- setenv.sh , I have created a setenv.sh in tomcat/bin, and the only think I added is the export JAVA_OPTS =”-Dmyprojectvar.subname=value -Danothervariable=value -Danother.variable=value” I dont know, is this enough to set the properties. I just want to add three properties to tomcat as system property using setenv.sh. What should I do to complete it successfully? What are the steps for it?I saw this question setenv.sh is not working in http://stackoverflow.com/. No is answer given there and ,even ,I don't understand the question. ie, Do we need to set CATALINA_HOME and other properties somewhere in setenv.sh?.

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  • Force Run System File Checker (SFC.exe)

    - by Zuck
    C:\Windows\system32>sfc /scannow Beginning system scan. This process will take some time. There is a system repair pending which requires reboot to complete. Restart Windows and run sfc again. Is there a way I can force SFC to scan again and make the new fixes on reboot? Probably by deleting some file or something? I removed C:\Windows\WinSxS\pending.xml by taking ownerships but it still shows the same message.

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  • Solution to Manage and Monitor (Ubuntu) Machines

    - by Elmar Weber
    I'm looking for a tool like Canonical (system management and monitoring for Ubuntu) that is Open Source and free. The goal is to manage a dozen or so KVM machines for private testing purposes. I know of puppet and munin or RHQ as separate tools to manage and monitor, but I'd prefer something integrated. Any tips? Basic requirements would be: system package management and update (individual selection for each managed node) configuration of basic system services (Users, NFS, cron, ideally also Apache) monitoring (charting of system resources, disk, io, memory, etc) and alerting, ideally a default configuration with sensible values for alerts

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  • Is there a chroot build script somewhere?

    - by Nils
    I am about to develop a little script to gather information for a chroot-jail. In my case this looks (at the first glance) pretty simple: The application has a clean rpm-install and did install almost all files into a sub-directory of /opt. My idea is: Do a find of all binaries Check their library-dependencies Record the results into a list Do a rsync of that list into the chroot-target-directory before startup of the application Now I wonder - ist there any script around that already does such a job (perl/bash/python)? So far I found only specialized solutions for single applications (like sftp-chroot). Update I see three close-votes for the reason "off topic". This is a question that arose because I have to install that ancient piece of software on a server at work. So if you still feel this is off-topic - leave a comment...

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  • System Lags/Freezes when under high usgage

    - by tom
    I am not sure if its my GPU / Memory or Hard drive thats failing. For example if I'm runnning more than one instance of chrome and running an application that takes up a lot of resources, my system will start to lag and freeze. When I launch Photoshop the GPU feature disables automatically, this also lags when I click on menus and when working on documents in Photoshop. I really dont know where to start, if i should buy a new graphics card or test the memory or could it be my OS drive? System: Windows 7 64bit, ATI Raedeon 5850, Corsair 2x4GB http://i.stack.imgur.com/qqkLZ.jpg

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  • I need a script to lockdown the system time to users via gpedit.msc

    - by Chester
    I need to lockdown the system time on a number of PCs via gpedit.msc and then removing administrators from the group and then adding 'administrator' and 'polling'. Can I do this via a script? Essentially I have to; Run gpedit.msc Computer Configuration Windows Settings Security Settings Local Policies User Rights Assignment Double Click Change the system time Select Administrators Click Remove Click Add User or Group Type Administrator Click Check Names Type polling Click Check Names OK Apply OK Logoff I have to do this for a huge number of computers so is there a batch file I could run on each PC to do this? Your help would be very much appreciated. Best Regards

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  • Windows 7 system CPU bogged by windows services, no explanation

    - by Alex
    I'm looking at a laptop for a colleague which is running terribly slow. A quick look showed that the CPU was 100% used by 2-3 SVCHost processes, which off course doesn't tell much since those are just 'cover' processes with services running underneath them. So I fired up process explorer in hopes of finding a shady rogue service which was bogging the system, but to my suprise I found genuine MS Windows processes (or at least damn-good disguised ones) are bogging down the system: dnscache (DNS Client) IKEEXT (IKE and AuthIP IPSec Keyring modules) iphlpsvc (IP Helper) Seen separately, these processes might seem odd to be using a lot of CPU, but taking a step back one can conclude that all three services are quite closely related to networking. I've tried running: netsh int ip reset log.txt which has helped me save bizarre network-related problems in the past, but this didn't help Off course I though about a virus, but both MS Security Essentials as well as malwarebytes (let both run a full scan).

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  • WindowsXP+7 on C:/D: :moving the System Partition

    - by user938921
    I had installed Windows 7 on a separate 20gig partition, and I'm absolutely loving it! Plus I can now dual-boot, with my original WinXP residing on the C: drive. But I'm running out of disk space on D:, and I was able to shrink C: and expand D:. But now I would like to make D: not just a Boot Partition, but an Active System Partition, without losing my ability to boot into Windows 7 (since it was created on a separate D: partition, not the current Active System C: Partition). Any advice?

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  • Benefits of a RAID BBU in addition to a double UPS + PS system

    - by Wikser
    Today I roughly measured the benefits of enabling write-back on the RAID controller on a server at work. It got no RAID battery-backup-unit (BBU) so the write-cache is currently disabled. As the server is not used to capacity (by far), the results in most test were spectacular, e.g.: Database CRUD: before 35s, after 4s Saving a 1MB Excel file: before: 20s (!), after: 0.5s Of course having a BBU is always recommended, but what are the main benefits of installing a BBU to a system, which got redundant power supplies and is attached to UPSs? Does this depend on the type of the system (database, file, terminal)? What is a realistic fail scenario which could be prevented by a BBU? Thanks in advance!

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  • Operating system not found after downloading skin pack

    - by 8BitSensei
    My brother has downloaded a executable file from Skin Pack — I believe it was the Mountain Lion IO6 skin pack. He's using an Acer Aspire 553G. And now his operating system won't start (Windows 7). It gets to the BIOS and then goes to load up the OS but the screen goes blank and it just goes back to the BIOS over and over again. He decided to play with the bootup settings and tried different options and got the error message "Operating System not found." Does anyone have any idea how to solve this?

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  • VMware Workstation 7 build 203739 - Capture Movie Mouse Pointer Not Visible

    - by BMIVM
    Hi, I have noticed that whenever I create a Capture Movie, the movie is fine but the mouse pointer is not visible at all. The clicks are on buttons file menus are executed but is hard for a viewer of the capturre movie session to follow the recording smoothly. This was not a problem in previous versions of WorkStation. Is this a bug or is there a setting I can set to see the mouse pointer? Note: VM Tools are installed, Host is Vista Ultimate Edtion SP1, x64 and the guest is a Win XP SP2. Thanks in advance for your help.

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  • missing windows/system32/config/system

    - by Faruq Sandi
    i know it is common problem, but not its so strange. problem: common missing windows/system32/config/system what i do next: put hdd to another pc and boot from it, it is succeeded but without warning window after startup that says like "windows has recovered from serious problem". and than i put back hdd to previous pc. tadaaa!!!! missing windows/system32/config/system is happening again! now i am trying repair this problem with recovery console from CD. i hope it will successful. someone can explain this? what should i do?

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  • Is there any way to shut up my ATI HD 5770?

    - by slpsys
    So to preface, I basically built Jeff's machine; I already had some of the components, including (scarily enough) the exact same case1. I've been buying bits and pieces over the past few months, which coincided perfectly with his recent post about three monitors, though not being a gamer outright, I opted for the second-from-the-bottom option. After finally plopping all the pieces lovingly into the case this evening, I turn it on...and it sounds like four professional grade hair-driers. Some quick regression analysis determined that with the video card out, the running machine sounded no louder than our house's vents. Basically, my last desktop build included a $45-at-the-time graphics card, and it's been Macbook Pros and workstations since then, so I have zero idea whether I'll just be able to tune the fan speed later on. Will I be able to get this thing to quiet down every time I'm not playing Modern Warfare 2 at maximum framerate, or should I just send this thing back now, and get the quietest card in my pricerange? 1 One thing of note is that I do not have noise-absorbing foam in the case, as is pictured in the article. I'm only mentioning that because I suspect it could drop the overall output a few decibels, but obviously not that many.

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  • how to build network across buildings ?

    - by Omie
    Hi ! I need some help in building a network between hundreds of computers spread across multiple buildings of my college. Yes, I'll be doing this as a part of my college project. Please see this image, it will give you enough idea of what I'm trying to achieve. http://i.imgur.com/rOohx.png All the computers in all buildings should be able to connect server. Once network is up, there will be a set of services over intranet and network use will be moderate. well, say there will be an email server and a http server. My point is, I cannot afford much of performance loss. It feels easy to connect computers inside 1 building to each other, however, I'm clueless as to how to connect all of them to server. I mean, just 1 cable won't be enough to connect 1 building to server, right ? How should I go with it ? I am not expecting detailed configuration. Just heads up will do :) Thanks

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  • Trying to build a history of popular laptop models

    - by John
    A requirement on a software project is it should run on typical business laptops up to X years old. However while given a specific model number I can normally find out when it was sold, I can't find data to do the reverse... for a given year I want to see what model numbers were released/discontinued. We're talking big-name, popular models like Dell Latitude/Precision/Vostro, Thinkpads, HP, etc. The data for any model is out there but getting a timeline is proving hard. Sites like Dell are (unsurprisingly) geared around current products, and even Wikipedia isn't proving very reliable. You'd think this data must have been collated by manufacturers or enthusiasts, surely?

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  • OAuth Consumer request for token from ServiceProvider returns InternalServerError

    - by chridam
    I'm playing around with DevDefined.OAuth - an OAuth consumer and provider implementation for .Net http://code.google.com/p/devdefined-tools/wiki/OAuth and on launching the ExampleConsumerSite project after configuring the service endpoints on my IIS 7 web server, I'm receiving the following error: Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. Exception Details: System.Exception: Request for uri: http://localhost%3A8080/RequestToken.aspx?oauth%5Fcallback=oob&oauth%5Fnonce=94efde0b-dd45-4cee-8253-7496cef0b877&oauth%5Fconsumer%5Fkey=key&oauth%5Fsignature%5Fmethod=PLAINTEXT&oauth%5Ftimestamp=1252512419&oauth%5Fversion=1.0&oauth%5Ftoken=&oauth%5Fsignature=secret%2526 failed. status code: InternalServerError An error occurred during the parsing of a resource required to service this request. Please review the following specific parse error details and modify your source file appropriately. Source Error: [HttpException]: 'RequestToken' is not allowed here because it does not extend class 'System.Web.UI.Page'. at System.Web.UI.TemplateParser.ProcessError(String message) at System.Web.UI.TemplateParser.ProcessInheritsAttribute(String baseTypeName, String codeFileBaseTypeName, String src, Assembly assembly) at System.Web.UI.TemplateParser.PostProcessMainDirectiveAttributes(IDictionary parseData) [HttpParseException]: 'RequestToken' is not allowed here because it does not extend class 'System.Web.UI.Page'. at System.Web.UI.TemplateParser.ProcessException(Exception ex) at System.Web.UI.TemplateParser.ParseStringInternal(String text, Encoding fileEncoding) at System.Web.UI.TemplateParser.ParseString(String text, VirtualPath virtualPath, Encoding fileEncoding) [HttpParseException]: 'RequestToken' is not allowed here because it does not extend class 'System.Web.UI.Page'. at System.Web.UI.TemplateParser.ParseString(String text, VirtualPath virtualPath, Encoding fileEncoding) at System.Web.UI.TemplateParser.ParseReader(StreamReader reader, VirtualPath virtualPath) at System.Web.UI.TemplateParser.ParseFile(String physicalPath, VirtualPath virtualPath) at System.Web.UI.TemplateParser.ParseInternal() at System.Web.UI.TemplateParser.Parse() at System.Web.UI.TemplateParser.Parse(ICollection referencedAssemblies, VirtualPath virtualPath) at System.Web.Compilation.BaseTemplateBuildProvider.get_CodeCompilerType() at System.Web.Compilation.BuildProvider.GetCompilerTypeFromBuildProvider(BuildProvider buildProvider) at System.Web.Compilation.BuildProvidersCompiler.ProcessBuildProviders() at System.Web.Compilation.BuildProvidersCompiler.PerformBuild() at System.Web.Compilation.BuildManager.CompileWebFile(VirtualPath virtualPath) at System.Web.Compilation.BuildManager.GetVPathBuildResultInternal(VirtualPath virtualPath, Boolean noBuild, Boolean allowCrossApp, Boolean allowBuildInPrecompile) at System.Web.Compilation.BuildManager.GetVPathBuildResultWithNoAssert(HttpContext context, VirtualPath virtualPath, Boolean noBuild, Boolean allowCrossApp, Boolean allowBuildInPrecompile) at System.Web.Compilation.BuildManager.GetVirtualPathObjectFactory(VirtualPath virtualPath, HttpContext context, Boolean allowCrossApp, Boolean noAssert) at System.Web.Compilation.BuildManager.CreateInstanceFromVirtualPath(VirtualPath virtualPath, Type requiredBaseType, HttpContext context, Boolean allowCrossApp, Boolean noAssert) at System.Web.UI.PageHandlerFactory.GetHandlerHelper(HttpContext context, String requestType, VirtualPath virtualPath, String physicalPath) at System.Web.UI.PageHandlerFactory.System.Web.IHttpHandlerFactory2.GetHandler(HttpContext context, String requestType, VirtualPath virtualPath, String physicalPath) at System.Web.HttpApplication.MapHttpHandler(HttpContext context, String requestType, VirtualPath path, String pathTranslated, Boolean useAppConfig) at System.Web.HttpApplication.MapHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) I've noticed the oauth_token GET parameter is empty. On tracing this, the error source is from the line 12 of Default.aspx.cs page: IToken requestToken = session.GetRequestToken(); protected void oauthRequest_Click(object sender, EventArgs e) { OAuthSession session = CreateSession(); IToken requestToken = session.GetRequestToken(); if (string.IsNullOrEmpty(requestToken.Token)) { throw new Exception("The request token was null or empty"); } Session[requestToken.Token] = requestToken; string callBackUrl = "http://localhost:" + HttpContext.Current.Request.Url.Port + "/Callback.aspx"; string authorizationUrl = session.GetUserAuthorizationUrlForToken(requestToken, callBackUrl); Response.Redirect(authorizationUrl, true); } While I'm not sure if this has to do with configuring the service endpoints but I'm running the consumer project from VS2008 and hosting the service on IIS. Please advice.

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  • Manage a flexible and elastic Data Center with Oracle VM Manager (By Tarry Singh - PACKT Publishing)

    - by frederic.michiara
    For the ones looking at an easy reading and first good approach to Oracle VM Manager and VM Servers, I would recommend reading the following book even so it was written for 2.1.2 whereas we can use now Oracle VM 2.2 : Oracle VM Manager 2.1.2 Manage a Flexible and Elastic Data Center with Oracle VM Manager Learn quickly to install Oracle VM Manager and Oracle VM Servers Learn to manage your Virtual Data Center using Oracle VM Manager Import VMs from the Web, template, repositories, and other VM formats such as VMware Learn powerful Xen Hypervisor utilities such as xm, xentop, and virsh A practical hands-on book with step-by-step instructions Oracle VM experts might be frustrated, but to me it's not aim to Oracle VM experts, but to the ones who needs an introduction to the subject with a good coverage of all what you need to know. This book is available on https://www.packtpub.com/oracle-vm-manager-2-1-2/book Need to find out about Table of contents : https://www.packtpub.com/article/oracle-vm-manager-2-1-2-table-of-contents Discover a sample chapter : https://www.packtpub.com/sites/default/files/sample_chapters/7122-oracle-virtualization-sample-chapter-4-oracle-vm-management.pdf Read also articles from Tarry Singh on http://www.packtpub.com/ : Oracle VM Management : http://www.packtpub.com/article/oracle-vm-management-1 Extending Oracle VM Management : http://www.packtpub.com/article/oracle-vm-management-2 Hope you'll enjoy this book as a first approach to Oracle VM. For more information on Oracle VM : Oracle VM on n OTN : http://www.oracle.com/technology/products/vm/index.html Oracle VM Wiki : http://wiki.oracle.com/page/Oracle+VM Oracle VM on IBM System x : http://www-03.ibm.com/systems/x/solutions/infrastructure/erpcrm/oracle/virtualization.html

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  • When Do OS Questions Belong on Hardware Service Requests?

    - by Get Proactive Customer Adoption Team
    Untitled Document My Oracle Support—Logging an Operating System Service Request One of the concerns we hear from our customers with Premier Support for Systems is that they have difficulty logging a Service Request (SR) for an operating system issue. Because Premier Support for Systems includes support for the hardware and the associated operating system, you log any operating system issues through a hardware Service Request. To create a hardware Service Request, you enter the information into the Hardware tab of the Create Service Request screen, but to ensure that the hardware Service Request you enter is recognized and routed appropriately for an operating system issue, you need to change the product from your specific hardware to the operating system that the hardware is running. The example below shows you how to create a Service Request for the operating system when the support level is Premier Support for Systems. The key to success is remembering that the operating system coverage is part of the hardware support. To begin, from anywhere within My Oracle Support, click on the Create SR button as you would to log any SR: Enter your Problem Summary and the Problem Description Next, click on the Hardware tab. Enter the System Serial Number (in this case “12345”) and click on Validate Serial Number: Notice that the product name for the hardware indicates “Sunfire T2000 Server” with an option for a drop down List of Values. Click on the product drop down and choose the correct operating system from the list. In this case I have chosen “OpenSolaris Operating System” Next, you will need to enter the correct operating system version: At this point, you may proceed to complete and submit the Service Request. If your company has Premier Support for Systems, just remember that your operating system has coverage under the hardware it runs on, so start with a Hardware tab on the Service Request screen and change the product related information to reflect the operating system you need help with. Following these simple steps will ensure that the system assigns your Service Request to the right support team for an operating system issue and the support engineer can quickly begin working your issue.

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  • Create a Shortcut To Group Policy Editor in Windows 7

    - by Mysticgeek
    If you’re a system administrator and find yourself making changes in Group Policy Editor, you might want to make a shortcut to it. Here we look at creating a shortcut, pinning it to the Taskbar, and adding it to Control Panel. Note: Local Group Policy Editor is not available in Home versions of Windows 7. Typing gpedit.msc into the search box in the Start menu to access Group Policy Editor can get old fast. To create a shortcut, right-click on the desktop and select New \ Shortcut. Next type or copy the following path into the location field and click Next. c:\windows\system32\gpedit.msc Then give your shortcut a name…something like Group Policy, or whatever you want it to be and click Finish. Now you have your Group Policy shortcut… If you want it on the Taskbar just drag it there to pin it. And that’s all there is to it!   If you want to change the icon, you can use one of the following guides… Customize Icons in Windows 7 Change a File Type Icon in Windows 7 Add Group Policy to Control Panel If you’re using non Home versions of XP, Vista, or Windows 7, check out The Geek’s article on how to Add Group Policy Editor to Control Panel. Similar Articles Productive Geek Tips Add Group Policy Editor to Control PanelQuick Tip: Disable Search History Display in Windows 7Remove Shutdown and Restart Buttons In Windows 7How To Disable Control Panel in Windows 7Allow Users To Run Only Specified Programs in Windows 7 TouchFreeze Alternative in AutoHotkey The Icy Undertow Desktop Windows Home Server – Backup to LAN The Clear & Clean Desktop Use This Bookmarklet to Easily Get Albums Use AutoHotkey to Assign a Hotkey to a Specific Window Latest Software Reviews Tinyhacker Random Tips Acronis Online Backup DVDFab 6 Revo Uninstaller Pro Registry Mechanic 9 for Windows Fun with 47 charts and graphs Tomorrow is Mother’s Day Check the Average Speed of YouTube Videos You’ve Watched OutlookStatView Scans and Displays General Usage Statistics How to Add Exceptions to the Windows Firewall Office 2010 reviewed in depth by Ed Bott

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  • Installation taking a very long time, hangs at "Configuring bcmwl-kernel-source"

    - by user290522
    I am installing Ubuntu 14.04(32-bit) on my laptop (Compaq Presario V2000), and after about 7 hours, it is still in Configuring bcmwl-kernel-source (i386) mode. The messages I read are as follows: ubuntu kernel: [22814.858163] ACPI: \_SB_.PCI0.LPC0.LPC0.ACAD: ACPI_NOTIFY_BUS_CHECK event: unsupported with the numbers in the square brackets increasing. I have had Windows XP professional on this laptop, and I am erasing it. I am not sure if I should turn off the laptop, and start all over again. About 4 years ago I installed Ubuntu on this laptop, and that was very fast. The only problem I encountered was my wireless, and could not make it to work, and switched back to Windows. I appreciate any comments regarding this installation taking such a long time. After 40 hours the installation was still in configuring mode with the following messages: ubuntu CRON[29329]: (root) CMD ( cd/ && run-part .. report /etc/cron-hourly) I did the following to check for errors: pressed ctrl-alt-f2. This time the system froze. I had no other choice but to turn off the laptop, and start all over again. The exact model of the laptop is "Compaq Presario V2069CL Notebook PC" with AMD processor.

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  • How to find out which python script is using resources?

    - by Jesse the Wind Wanderer
    Can someone tell me how to find out which python script is using lots of system resources? I can see with the 'top' command that a process called "python" is always near the top of the list. 2603 jesse 20 0 159m 27m 13m S 6 1.4 1:47.74 python Can someone tell me how to find this specific python script's name? I could go through the arduous process of disabling startup apps/processes until I finally found the one that starts this python process but there must be a better way of determining what exactly this python process is, yes? Doing a ps -AH doesn't yield anything useful. ps -AH 1 ? 00:00:00 init ... 1325 ? 00:00:00 lightdm 1382 tty7 00:01:57 Xorg 2265 ? 00:00:00 lightdm 2510 ? 00:00:00 gnome-session 2546 ? 00:00:00 ssh-agent 2560 ? 00:00:02 gnome-settings- 2582 ? 00:00:01 syndaemon 2578 ? 00:00:49 compiz 3009 ? 00:00:00 sh 3010 ? 00:00:01 gtk-window-deco 2590 ? 00:00:00 nm-applet 2591 ? 00:00:00 bluetooth-apple 2592 ? 00:00:00 indicator-ubunt 2593 ? 00:00:00 gnome-fallback- 2600 ? 00:00:05 nautilus 2601 ? 00:00:00 everpad 2603 ? 00:02:24 python

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  • SQL SERVER – 2012 – List All The Column With Specific Data Types in Database

    - by pinaldave
    5 years ago I wrote script SQL SERVER – 2005 – List All The Column With Specific Data Types, when I read it again, it is very much relevant and I liked it. This is one of the script which every developer would like to keep it handy. I have upgraded the script bit more. I have included few additional information which I believe I should have added from the beginning. It is difficult to visualize the final script when we are writing it first time. I use every script which I write on this blog, the matter of the fact, I write only those scripts here which I was using at that time. It is quite possible that as time passes by my needs are changing and I change my script. Here is the updated script of this subject. If there are any user data types, it will list the same as well. SELECT s.name AS 'schema', ts.name AS TableName, c.name AS column_name, c.column_id, SCHEMA_NAME(t.schema_id) AS DatatypeSchema, t.name AS Datatypename ,t.is_user_defined, t.is_assembly_type ,c.is_nullable, c.max_length, c.PRECISION, c.scale FROM sys.columns AS c INNER JOIN sys.types AS t ON c.user_type_id=t.user_type_id INNER JOIN sys.tables ts ON ts.OBJECT_ID = c.OBJECT_ID INNER JOIN sys.schemas s ON s.schema_id = t.schema_id ORDER BY s.name, ts.name, c.column_id I would be very interested to see your script which lists all the columns of the database with data types. If I am missing something in my script, I will modify it based on your comment. This way this page will be a good bookmark for the future for all of us. Reference : Pinal Dave (http://blog.SQLAuthority.com) Filed under: PostADay, SQL, SQL Authority, SQL DMV, SQL Query, SQL Server, SQL System Table, SQL Tips and Tricks, T SQL, Technology

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  • Duck checker in Python: does one exist?

    - by elliot42
    Python uses duck-typing, rather than static type checking. But many of the same concerns ultimately apply: does an object have the desired methods and attributes? Do those attributes have valid, in-range values? Whether you're writing constraints in code, or writing test cases, or validating user input, or just debugging, inevitably somewhere you'll need to verify that an object is still in a proper state--that it still "looks like a duck" and "quacks like a duck." In statically typed languages you can simply declare "int x", and anytime you create or mutate x, it will always be a valid int. It seems feasible to decorate a Python object to ensure that it is valid under certain constraints, and that every time that object is mutated it is still valid under those constraints. Ideally there would be a simple declarative syntax to express "hasattr length and length is non-negative" (not in those words. Not unlike Rails validators, but less human-language and more programming-language). You could think of this as ad-hoc interface/type system, or you could think of it as an ever-present object-level unit test. Does such a library exist to declare and validate constraint/duck-checking on Python-objects? Is this an unreasonable tool to want? :) (Thanks!) Contrived example: rectangle = {'length': 5, 'width': 10} # We live in a fictional universe where multiplication is super expensive. # Therefore any time we multiply, we need to cache the results. def area(rect): if 'area' in rect: return rect['area'] rect['area'] = rect['length'] * rect['width'] return rect['area'] print area(rectangle) rectangle['length'] = 15 print area(rectangle) # compare expected vs. actual output! # imagine the same thing with object attributes rather than dictionary keys.

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