This example displays all the NorthWind Products with the same starting letter. The Query Substitution variable is used to select the appropriate results. 

The format of the Query Substitution variable is [Query:<key>:<defaultvalue>], so with the first visit to the page, the following Select Statement

Select * from Products where Left(ProductName,1) = '[Query:Letter:?]'

SQSV will use the default as no query paramter "Letter" is found. The resulting the select is

Select * from Products where Left(ProductName,1) = '?'

which returns no values.  The No Results Found option is enable to display a message to select one of the letters. 

Each letter is a link to the same page with added query parameter of "Letter=X" where X represents the appropriate letter in the link.  For example, selecting Link "A" will result in the following Select statement:

Select * from Products where Left(ProductName,1) = 'A'