A very pleasant surprise when building reports. There’s a new function called “queryValue”.

On the surface it looks fairly innocuous, but the result of this is a lot of effort saved when building reports. There are many times where I want a way of pulling a default value from a database in a filter. For example, my report might need to let the user select a year, but last date with data is unknown. Normally we can do something like:

[Sales (query)].[Time].[Year] = #prompt('Year','integer',
'maximum([Sales (query)].[Time].[Year] for report)'
)#

WITH 
"TQ0_q_SelectedMonth1" AS 
    (
    SELECT
        "GO_TIME_DIM"."CURRENT_YEAR" AS "Year0", 
        MAX("GO_TIME_DIM"."CURRENT_YEAR")
            OVER(
            ) AS "Max1"
    FROM
        "GOSALESDW"."gosalesdw"."GO_TIME_DIM" "GO_TIME_DIM"
    )
SELECT
    "TQ0_q_SelectedMonth1"."Year0" AS "Year0"
FROM
    "TQ0_q_SelectedMonth1" 
WHERE 
    "TQ0_q_SelectedMonth1"."Year0" = "TQ0_q_SelectedMonth1"."Max1" 
GROUP BY 
    "TQ0_q_SelectedMonth1"."Year0"

It works, but I don’t like it. It’s creating a window function, and actually hits every row in that table. One way around would be to create a parameter map in the framework model. Create a model query that has the value you want, add a data item with a static 1, and create a parameter map based on that. You could then do:
[Sales (query)].[Time].[Year] = #prompt('Year','integer',
sq($lastYearWithData{1})
)#

Then the SQL will look like:

SELECT
    "GO_TIME_DIM"."CURRENT_YEAR" AS "Year0"
FROM
    "GOSALESDW"."gosalesdw"."GO_TIME_DIM" "GO_TIME_DIM" 
WHERE 
    "GO_TIME_DIM"."CURRENT_YEAR" = 2013 
GROUP BY 
    "GO_TIME_DIM"."CURRENT_YEAR"

This is much better but still way too clunky. It requires access to the framework model, and a new parameter map for each and every scenario that we need. What if we want the last date of data for a specific product line? Or product?

Instead, let’s take a look at queryValue()

[Fact Business].[Dates].[Year] = #prompt('Year','integer'
, queryValue('maximum([Sales (query)].[Time].[Year])')
)#

This behaves exactly like the parameter map, and the SQL is identical. Cognos is actually making a query that runs maximum([Year]), and returns that value to the macro – exactly like a parameter map would. We can add filters to the query like this:
[Sales (query)].[Time].[Year] = #prompt('Year','integer',
queryValue('maximum([Sales (query)].[Time].[Year])','[Sales (query)].[Sales].[Quantity]>0 and [Sales (query)].[Products].[Product]=''Trail Star''')
)#

Notice using a double quote to escape the single quote. Great Outdoors stopped selling Trail Star in 2011, and 2011 is now the default value in the prompt.

This is also especially useful in Data Sets and Data Modules, where parameter maps simply don’t exist.