Archive
DSL Tools Preview available
DSL tools December CTP is available on MSDN downloads. Quite an interesting topic.
From Jochen Seemann‘s blog
A Neat little SQL Server Enterprise Manager Tip
From Scott Mitchell’s blog:
"hit Ctrl+C on a table name and then go to a text editor and hit Ctrl+V and get the appropriate CREATE TABLE SQL syntax for the “copied” table (which includes constraints)"
Really Really Cool.
ASP.NET: Scrollable datagrid with a fixed header
A colleague of mine had a requirement for a scrollable datagrid with a fixed header. Well, this may not be the best way to design UIs for the web. But in some cases the clients are demanding features as if it were a desktop application. Coming back to the problem, Google pointed to quite a few solutions. I was impressed by Dino Esposito’s solution on http://www.codearchitects.com
http://www.codearchitects.com/casubscription/Default.aspx (you need to sign up to download).
Other related links:
http://datawebcontrols.com/faqs/CustomizingAppearance/ScrollableDataGridWithFixedHeader.shtml
Modelling trees for RDBMS
An interesting problem on how to model tree structures with RDBMS came up this week. Google again came to the rescue. There are two approaches to model hierarchies in a RDBMS. The commonly used one is the adjacency list model
emp boss salary
===========================
‘Albert’ ‘NULL’ 1000.00
‘Bert’ ‘Albert’ 900.00
‘Chuck’ ‘Albert’ 900.00
‘Donna’ ‘Chuck’ 800.00
‘Eddie’ ‘Chuck’ 700.00
‘Fred’ ‘Chuck’ 600.00
Problem with the adjacency list model is that the boss and employee columns are the same kind ( names of personnel) and therefore should be shown in only one column in a normalized table.
A more efficient way would be the nested sets model
emp lft rgt
======================
‘Albert’ 1 12
‘Bert’ 2 3
‘Chuck’ 4 11
‘Donna’ 5 6
‘Eddie’ 7 8
‘Fred’ 9 10
Albert (1,12)
/
/
Bert (2,3) Chuck (4,11)
/ |
/ |
/ |
/ |
Donna (5,6) Eddie (7,8) Fred (9,10)
Imagine a little worm crawling anti-clockwise along the tree. Every time he gets to the left or right side of a node, he numbers it. The worm stops when he gets all the way around the tree and back to the top.
Here are two common queries which can be used to build others:
1. An employee and all their Supervisors, no matter how deep the tree.
SELECT P2.*
FROM Personnel AS P1, Personnel AS P2
WHERE P1.lft BETWEEN P2.lft AND P2.rgt
AND P1.emp = :myemployee;
2. The employee and all subordinates. There is a nice symmetry here.
SELECT P2.*
FROM Personnel AS P1, Personnel AS P2
WHERE P1.lft BETWEEN P2.lft AND P2.rgt
AND P2.emp = :myemployee;
This approach will be two to three orders of magnitude faster than the adjacency list model for subtree and aggregate operations.
From a post by Joe Celko on the microsoft.public.sqlserver.programming newsgroup:
http://groups.google.co.in/groups?hl=en&lr=&selm=93kor0%24bls%241%40nnrp1.deja.com&rnum=3
Another good article can be found @ http://www.yafla.com/papers/sqlhierarchies/sqlhierarchies.htm
Also looks like SQL for Smarties will be a good book to read.
Chameleon Clock – A neat little program
Check this one – A cool replacement for the system tray clock.
Web Services and Binary payload
Just ran into a request from one of colleagues on how to handle file attachments in Web Services.
Google pointed me this article on MSDN.
This uses DIME. DIME is now giving way to SOAP MTOM. http://www.w3.org/TR/2004/WD-soap12-mtom-20040608/
But as of now I believe the option is to go with DIME as WSE still doesn’t support MTOM.
Read this if need further background.
http://www.winfx247.com/247reference/msgs/0/1206.aspx
Another approach is outlined @
http://www.codeproject.com/cs/webservices/DIMEBridge.asp?print=true
TreeView Internet Explorer Web Control – TreeNodeSrc File locking issue
One of my friends ran into an issue with the TreeView Internet Explorer Web Control. It looked like ASP.NET worker process was maintaining a lock on the xml file.
Did a google search and ran into this post on ASP.NET forums. The last but one post was the solution.
http://www.asp.net/Forums/ShowPost.aspx?tabindex=1&PostID=331111
Express Manager – Can’t wait
Can’t wait to get my hands on SQL Server 2005 Express Manager December CTP.
SQL Server – Case When statements
Well, saw some strange behaviour with case when statements.
In each of the when statements, I select a different column.
Looks like even if one of the columns is an int and others varchar, SQL Server tries to convert the varchar columns to int.
If i put an explicit convert on the int column to varchar there is no such attempt to convert.
Hmm… Pretty strange for me though. Thanks to my friend Venky, for helping me in finding this one.
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