MS SQL Column Alias

T-SQL used in Microsoft SQL Server seem to have very limited support for column alias. If you have a complex calculated column that you want to re-use in GROUP, SELECT or another expression, it will be desirable to use alias to reference the same definition everywhere so that we can have a clear and easier to understand SQL statement.


Here is an article that is very helpful in this matter: Avoid Transact-SQL's Column Alias Limitations

Key points:

• MS SQL only allow alias in SELECT and ORDER BY
• Use sub-query, can help in some cases to re-use column alias
  

Coldfusion web services call return error: java.lang.NullPointerException

Turns out Coldfusion web services return data may contain pointer, and the receiving side will try to interpret that pointer. Once we commented out the offending data (a 2D array) in return, the error is gone.

DELL Quickset for Latitude E-Family

Just got a new Dell Latitude E6510 laptop. However, cannot find the familiar Dell Quickset on it.

After a couple of days' casual research, I finally found the answer: Dell Control Point is the new Quickset for Latitude E-Family.

As a side note, I like E6510.
Pros:

• Fast
  
• Bright screen
• Nice keyboard: backlight, good touch
  
• Multi-touch, allow pinch zoom, rotations, and other gesture
• ... more
  

Cons: none so far.

Syntax Highlighting on Blogger - Gist

Here is another way to paste code into blogger with nice syntax highlighting.

1. Go to http://gist.github.com
2. Past the code you want to post
3. Copy the embed tag
4. Go back to blogger, and select "Edit Html"
5. Paste the embed tag into your post

Below is the example source code using this tag: <script src="http://gist.github.com/467670.js?file=gistfile1.sql"></script>




A potential drawback of this approach might be the stability of github as a company. In a downturn, it may shut down with very short notice.

Compare to using SyntaxHighlighter, personally, I think this approach is way better:

1. No setup required (in a previous post I documented how to setup syntaxhighlighter for blogger, it took me half an hour to setup everything correctly. Now with gist, there is zero setup required );
2. Faster to create code snippet in a post;
3. Supports more languages;
4. No need to worry about pasting XML, HTML, or other special characters;

To paste script like below used to require replacing '<' with &lt; and '>' with &gt; manually. Now is simply copy paste without any manual changes:

Flex Builder Error 1046: "Type was not found or was not a compile-time constant"

Problem:
While editing a big .as file in Flex Builder 3, the compile is broken suddenly. Got this error:

1046: Type was not found or was not a compile-time constant: ?????.

Cause:
Seems like Flex editor tend to wrongly remove import statement at the top of .as file without user consent.

Solution:
Disable Flex Builder feature:
Windown > Preferences > Flex > Editors > ActionScript Code, uncheck "Remove unused imports when organizing"

ColdFusion Builder Error: "Unhandled event loop execution"

Environment: Eclipse 3.5, ColdFusion Builder Plugin, Aptana

Problem:
Whenever I open a Coldfusion file, will see error "Unhandled event loop exception." followed by a dialog: "An error has occured. See error log for more details. CFMOutlinePage_0".

Cause:
Turns out CF Builder is using Aptana which conflict with the lastest Aptana.

Solution:
Disable Aptana:

• Disable Aptana: Windows -> Preferences -> General -> Startup and Shutdown, uncheck all Aptana plugins;
• Disable Aptana Update: Windows -> Preferences -> Install/Update -> Available Software Sites, disabled all Aptana sites;
• Restart Eclipse using the "-clean" command line, and the problem seems to be fixed now.

Another riskier solution is to uninstall Aptana Studio from Eclipse.

• Copy current Eclipse directory for backup;
• Help > About Eclipse > Installation Details > Installed Software > Aptana Studio > Uninstall
  

More Info:
---------------Detailed Error Log-------------------------
eclipse.buildId=
java.version=1.6.0_20
java.vendor=Sun Microsystems Inc.
BootLoader constants: OS=win32, ARCH=x86, WS=win32, NL=en_US
Framework arguments: -product org.eclipse.epp.package.jee.product
Command-line arguments: -os win32 -ws win32 -arch x86 -product org.eclipse.epp.package.jee.product -clean


Error
Tue Jun 29 10:45:04 PDT 2010
Unhandled event loop exception

org.eclipse.swt.SWTException: Failed to execute runnable (java.lang.NoSuchFieldError: EditorUpdaterThread_0)
at org.eclipse.swt.SWT.error(SWT.java:3884)
at org.eclipse.swt.SWT.error(SWT.java:3799)
at org.eclipse.swt.widgets.Synchronizer.runAsyncMessages(Synchronizer.java:137)
at org.eclipse.swt.widgets.Display.runAsyncMessages(Display.java:3885)
at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3506)
at org.eclipse.ui.internal.Workbench.runEventLoop(Workbench.java:2405)
at org.eclipse.ui.internal.Workbench.runUI(Workbench.java:2369)
at org.eclipse.ui.internal.Workbench.access$4(Workbench.java:2221)
at org.eclipse.ui.internal.Workbench$5.run(Workbench.java:500)
at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332)
at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:493)
at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:149)
at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:113)
at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:194)
at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:110)
at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:79)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:368)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:179)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:559)
at org.eclipse.equinox.launcher.Main.basicRun(Main.java:514)
at org.eclipse.equinox.launcher.Main.run(Main.java:1311)
Caused by: java.lang.NoSuchFieldError: EditorUpdaterThread_0
at com.adobe.ide.editor.cfml.EditorUpdaterThread.createDelayedRefreshJob(EditorUpdaterThread.java:340)
at com.adobe.ide.editor.cfml.EditorUpdaterThread.access$1(EditorUpdaterThread.java:338)
at com.adobe.ide.editor.cfml.EditorUpdaterThread$1.run(EditorUpdaterThread.java:265)
at org.eclipse.swt.widgets.RunnableLock.run(RunnableLock.java:35)
at org.eclipse.swt.widgets.Synchronizer.runAsyncMessages(Synchronizer.java:134)
... 22 more

-------------Screenshot of the error dialog--------------------------------------

Visaul Studio Strong Name Error - Importing key file "X.pfx" was canceled

Problem:
Getting a new computer, so I installed fresh Visual Studio 2010, and checked out source code from SVN. Then I got the following errors:

Cannot import the following key file: X.pfx. The key file may be password protected. To correct this, try to import the certificate again or manually install the certificate to the Strong Name CSP with the following key container name: VS_KEY_F...


Importing key file "X.pfx" was canceled

Solution:
Run this command line:
sn -i X.pfx VS_KEY_F...

Flex Compiler Error - Could not resolve * to a component implementation

While extending MX control ComboBox, I am trying to alter it's property.

<mx:dropdownfactory>
     <mx:component>
      <mx:tree change="outerDocument.updateLabel()" height="200" allowmultipleselection="{outerDocument.allowMultipleSelection}" showroot="{outerDocument.showRoot}" showdatatips="true" datatipfield="{outerDocument.labelField}">
   </mx:tree>
</mx:component>
</mx:dropdownfactory>

I got the compiler error as stated in the tile. Turns out I should refer to the property using my custom control's own name space. So the code should be like this:

<local:dropdownfactory>
     <mx:component>
      <mx:tree change="outerDocument.updateLabel()" height="200" allowmultipleselection="{outerDocument.allowMultipleSelection}" showroot="{outerDocument.showRoot}" showdatatips="true" datatipfield="{outerDocument.labelField}">
   </mx:tree>
</mx:component>
</local:dropdownfactory>

SQL 2005 on Windows XP SP3 - MSXML6 Error

Problem:
With a fresh Windows XP SP3, I cannot install SQL 2005. The error message in log file is:

Property(S): SupportedOSMessage = Installation of this product failed because it is not supported on this operating system. For information on supported configurations, see the product documentation.
Property(S): ShortCutText = MSXML 6 Service Pack 2 (KB973686)
Property(S): DialogTitle = MSXML 6 Service Pack 2 (KB973686) Setup
Property(S): ProductName = MSXML 6 Service Pack 2 (KB973686)
Property(S): ShortName = MSXML 6 Service Pack 2 (KB973686)
Property(S): WrongPackage = This MSXML6 Service Pack 2 (KB973686) package is not supported on the current processor type.
Property(S): DialogPatchTitle = MSXML 6 Service Pack 2 (KB973686) Patch
Property(S): SystemFolder = C:\WINDOWS\system32\

...

MSI (s) (04:A8) [09:38:47:725]: Product: MSXML 6 Service Pack 2 (KB973686) -- Configuration failed.

MSI (s) (04:A8) [09:38:47:725]: Windows Installer reconfigured the product. Product Name: MSXML 6 Service Pack 2 (KB973686). Product Version: 6.20.2003.0. Product Language: 1033. Reconfiguration success or error status: 1603.

Solution:
Luckily, I am not the first one who saw this problem. This problem seems to be around for a while now. There is a nice Microsoft KB article for this exact problem, and the solution is to use "Windows Installer CleanUp utility" to remove existing MSXML then install SQL 2005.

And, IT WORKS!!

Reference: MSKB 968749 http://support.microsoft.com/kb/968749

TSQL: Fixed Width Number Formatting

RIGHT('00000' + CAST(myNumber AS VARCHAR), 5)

MSDN Library is Gone in Visual Studio 2010

I consider this another major setback in Visual Studio 2010.

Visual Studio 2010 come with a help system that is the worst since Visual Studio 2002.

Pros:

• web-based, can be views in IE, as well as FireFox;
• Encourage the use of better search engines like Google?
  

Cons:

• No auto-complete search box;
• Search result is worse than Google;
• Left pane only has three fixed positions, cannot be resized or hidder;

To compensate the lack of auto-complete, I have stopped using my local help system and starting to use Google as my MSDN document explorer which did an excellent job.

Google Lost Touch with Users

Recently, Google made some major changes without giving user an option to use the old style.

I do not like their changes, mainly the bar on the left. It is duplicate of the bar on the top which I'm fine with.

Now, with the bar on the left, waste huge amount of space beneath it, I am forced to constantly scroll my browser horizontally to see the full content.

I'd rather to see ads fill that space. Then I know this is a decision driven by commercial interest.

Now, with those seemingly useless links which is neither good for me nor Google, I am completely puzzled.

How can I turn this sidebar off? Try a "GOOGLE SEARCH".

Dynamically Hide Cells in Flex DataGrid

Goal: Control visibility of controls in Flex DataGrid

Problem:
Control of cells' visibility in Flex DataGrid turns out to be pretty tricky. If you simply use inline item renderer and bind it's visibility attribute to a data provider, it won't work.

Why:
Fortunately, Flex is open source. So, we can dig a little deeper into why it does not work.

1. Look at SDK 3.2.0: DataGridBase.as, line 1073 will show that Flex SDK will actually set the renderer to visible after set "data" property of the control.
2. Also, the SDK may decide to hide the cell when it sees fit in various situations;
   

So, it is not desirable to control visibility directly. You are fighting with the SDK.

Solution(s):
Solution 1: Use a container as item renderer, and embed your control inside the container.
Pros: Quick and easy to implement. An added benefit is that you can control cell layout;
Cons: As all the Flex text book will stress: using too many containers is very BAD for performance! How bad? A 20X20 DataGrid may take at least 5 seconds to render!

Solution 2: Create custom control based on the control you want to use in the cell. And manage a new "forceHide" attribute, which will cooperate with the original "visible" attribute to decide a control's visibility. Please see the sample code below. Some details are missing, but you get the idea.

...
protected var _forceHide:Boolean = false;
/**
* visible by set method
*/        
protected var _setVisible:Boolean = false;
/**
* If set, this control will not be visible. It will overwrite visible property.
* DataGrid tend to manipulate visible directly, we can only use
* this extra field to force hide control even if DataGrid decides
* that it can be shown.
*/
public function set forceHide(value:Boolean):void {
    _forceHide = value;                          
    setVisible(_setVisible);
    invalidateProperties();
}
override public function setVisible(value:Boolean, noEvent:Boolean=false):void {
    //save desired settings
    _setVisible = value;
    //forceHide can mask out change request
    super.setVisible((!_forceHide) && value, noEvent);
}
...

Other Thoughts:
How about "CallLater"? It turns out to be a bad idea. As stated before, Flex SDK may want to hide some controls. If your "CallLater" set a control's visible to true, when Flex SDK think it is invisible, you may see some ghost controls hanging around.

Coldfusion Query of Queries (QoQ) Support

QoQ is convenient, but also poorly documented. I cannot find any official Adobe documentation with details about its features and limitations. It's features changes from version to version, usually only expanding (which is a good thing). There are also many bugs, and weird restrictions.

I guess Ben Forta's books rarely touched this topic for a reason.

So generally, I can only test what can be done by trial and error, and frequently find out that although it works on my computer, but will fail in another CF host due to difference in CF server version.

A summary of what can and cannot be done in CF QoQ (aka In Memory Query).
1. Data size: recommended 5,000 - 50,000 rows, subject to computer memory size;
2. join: inner join of two tables using WHERE clause
Can:
join two tables
inner join through a WHERE clause
cross join
Cannot:
use these clauses: LEFT JOIN, RIGHT JOIN, OUTER JOIN
join more than two tables
3. union: supported, but can be difficult to use due to strict type matching requirements;
4. dot notation: allow access to query in a structure through dot notation;
5. conditional operators: IS, IS (NOT) NULL, >, >=, <>, !=, <, <=, ==, BETWEEN, IN, LIKE
6. case sensitivity: it is case sensitive
7. other supported T-SQL keywords: GROUP, ORDER, DISTINCT, AVG, COUNT,

Beyond QoQ:
1. features from CFQuery tag: maxRows (equivalent to TOP), blockFactor
2. features from CFOutput, CFLoop: startRow, maxRows (combined equivalent to LIMIT)

Windows XP "System Restore" and Subversion

Subversion users be aware: Windows XP "System Restore" will rollback your SVN working folder!

Just learned it the hardway. I did a system restore on my Windows XP box, and all of sudden all the projects are broken. It turned out that all my SVN working folders are rolled back too.

Solutions?

1. Checkout "Head" from SVN repo again. Lucky for me, I do check-in frequently, and this solution works for me just fine;
2. Start "System Restore", and this time select "Undo my last restoration";
   

Subversion (SVN) Client for Windows Quick Start

This is a brief guide to SVN client usage on Windows using Tortoise SVN client.

Recommended Software:

1. Install Tortoise SVN client from this web site: tortoisesvn.tigris.org
2. Install winmerge from winmerge.org for merging code

Check out:To check out a project from SVN server for the first time: start Windows Explorer, right click in the folder you want to save the checkout code, and select "SVN Checkout".

Check in procedures:
Check-in usually have three steps in the following order:

1. add new file to server;
2. check for new updates from server and merge if necessary;
3. commit the changes back to the server;

Minimum requirement for the checked in code is that they can compile without errors.

More detailed checkin steps:
1. In windows explorer, right click the checkout root folder, and select “SVN Add”;
2. If new files are listed in the following dialog:
a. check the files that you want to send to SVN;
b. uncheck the files that you do not want to send to SVN, and add them to the ignore list;
3. Right click the root folder again, and select “SVN Update”
4. If there are changes or merge during update step, double check that the code can still compile;
5. Right click the root folder, and select “SVN Commit”, and type a proper comment about what are fixed, or the new features in this checkin;

Visaul Studio 2010 First Impression

It is officially released today. Tried a little bit and did not like it at all.

#1 problem: sluggish GUI response! No kidding. I thought Eclipse is slow, now I see something slower. No wonder it's release date was postponed to fix performance problem.

Of course, there is also problem finding my way around the IDE. Cannot seem to find a way to generate create script for my database project.

Lean Software Development

Some study notes while reading about Lean Software Development:

• Adapted from Lean Manufacturing, Toyota Production System;
  
• Originated in the boot "Lean Software Development" by Mary Poppendieck and Tom Poppendieck
  
• Principles:
  
  • Eliminate waste
    
    • Extra features
      
    • Economies of scale: focusing on high utilization is almost guaranteed to lower it
      
    • Cross boundaries
      
    
    
  • Amplify leaning
    
  • Decide as late as possible
    
  • Deliver as fast as possible
    
  • Empower the team
    
  • Build integrity in
    
  • See the whole
    
  
  
• Two pillars
  
  • Continuous improvement
    
  • Respect for people
    
  
  
• The responsibility lies, not with black belt specialist, but with the leadership hierachy that runs the operation and they are teachers and coaches;
  
• The essence of (the Toyota system) is that each individual employee is given the opportunity to find problems in his own way of working, to solve them and to make improvements;
• Challenge everything, dissatisfied with status quo
  
• Kanban
  
• Kaizen
  
  • spread knowledge
    
  • small, relentless
    
  • retrospectives
    
  • 5 whys
    
  • eyes for waste
    
  
  
• Share rather than enforce practices

Good References:

http://en.wikipedia.org/wiki/Lean_software_development

Lean Primer: http://www.leanprimer.com/downloads/lean_primer.pdf

http://www.poppendieck.com/

Flex Builder Error: "Unable to export SWC oem"

Solution: Right click on project, select Properties > Flex Library Build Path > Assets. Uncheck the root node and check it again, then compile project. The error is gone.

I found the solution here: http://flexdevtips.blogspot.com/2009/06/unable-to-export-swc-oem.html

Performance Optimization for Embedded Systems

Some key points:

• Load code and data as much as possible into internal memory (L1 cache);
• Use compiler or linker options to optimize for code size can sometimes give better performance than optimize for performance (GreenHills has a very nice tool to help find the optimum compromise between optimize for speed and size). Major points for manipulation:
  • Optimize for speed
  • Optimize for size
  • Remove unused functions
  • Remove debug information
  • Enable code cache
    

• Carefully tune the use of code cache and data cache. Performance difference between fine tuned layout and the default can be 10 time or more;
  
• Use integer, fixed point over float over double. If floating point computation is necessary, but double is not needed, then remember that all the constants MUST explicitly declared as floating precision, otherwise there may be a lot of double computation and float to double conversions. For example, instead of x=2.0; should use x=2.0f;
• Bit shift is faster than add (usually), add is faster than multiply (usually), multiply is faster than divide. So the following tricks usually are helpful:
  • Use left shift and right shift instead of multi and div by 2, 4, 8, 16, 32, ... (integer only);
    
  • Use add instead of multi 2, 3;
  • If a number is used as divider many times, pre-calculate it's inverse, and use multiply for the calculations;
• Blackfin (DSP architecture specific): assign data to A/B bank properly to enable parallel data retrieval;
• Profiler is your friend: use profiler to find the biggest consumer and focus on them;
• In C++ world: avoid deep hierarchy, because those practices take precious memory space which in turn have grave impact on performance;
• Be careful when you use C runtime. Call to "printf" can easily add 1k memory footprint;