SQL and Matrix math

Have you ever needed to do matrix multiplication in SQL, or multiply a matrix by a scalar? Here's an excellent article by Robyn Page and Phil Factor over at Simple-Talk about doing matrix math in SQL. It's surprisingly simple (relatively speaking, of course).

SQL Server Matrix Workbench

The keys to good software

There are four primary reasons good software is good software, claims Mike Elgan of Computerworld.

Consistency, simplicity, performance, and stability.

I agree. these are extremely well categorized. His point about simplicity nails it completely. Software has to be simple from it's design up through it's use by end-users. You cannot graft simplicity on after the fact.

Web 2.0 resources

Examples of Web 2.0 look-feel

Backpack
Aptana/

Design guides and tools

Web Design from Scratch
Photoshoplab.com
vandelaydesign.com

Arrays and SQL

An article that describes different techniques for faking arrays in SQL.

Faking Arrays in Transact SQL/

Here's a technique I wrote. It takes a delimited string and returns a results set. You can turn this into a function which returns a table variable too.

===========================================
create procedure usp_parse_string(@delimiter varchar(5), @parsestring varchar(1000))
as
SET NOCOUNT ON

declare @tempstring1 varchar(1000)
declare @tempstring2 varchar(1000)
declare @pos int, @oldpos int

create table #mytable (token_string varchar(100))

/* trim spaces of the string */
select @tempstring1 = ltrim(rtrim(@parsestring))
select @tempstring1 = REPLACE (@tempstring1, '"' , '' )
--select @tempstring1

/* see if delimiter is in string */
select @pos = charindex(@delimiter, @tempstring1)
/* select @tempstring2 */

/* if it is in the string, then get first token */
if @pos <> 0
begin
select @tempstring2 = substring(@tempstring1,1,@pos - 1)
--select @tempstring2
--insert it into the token table
insert into #mytable values (@tempstring2)
end

/* now get rest of tokens */
select @oldpos = @pos
select @pos = charindex(@delimiter, @tempstring1, @pos + 1)
while @pos <> 0
begin
select @tempstring2 = substring(@tempstring1, @oldpos + 1, @pos - @oldpos - 1)
insert into #mytable values (@tempstring2)
--select @tempstring2
select @oldpos = @pos
select @pos = charindex(@delimiter, @tempstring1, @pos + 1)
end

--get the last token
select @tempstring2 = substring(@tempstring1, @oldpos + 1, len(@tempstring1))
--select @tempstring2
insert into #mytable values (@tempstring2)

select * from #mytable

go
===========================================