SQL functions in Script Logic

Question

I want to build a script logic but the dimensions that I am testing do not have the fields I want in the format I want. In my case I would like to test the "Start" property in the Employee dimension. The property represents the employee start date but is a var char in the format dd.mm.yyyy rather thna a date field. I want to test whether it is five years prior to the date being processed.
My time dimension has a year property and a monthnum property. Each of these are varchar. I can write SQL that would convert these to a date and compare them with the start property on the employee dimension.
Can I  do iinsert SQL functions in the When statement. An example would be
*When convert(datetime, substring(employee.start,4,2) + '/' + substring(employee.start,1,2) + '/' + substring(employee.start,7,4))
Can I use  SQL functions in the Is statement? An example would be
*Is <DateAdd(YY,-5 , convert(datetime, Time.Monthnum + '/01/'' + time.year)
Finally when I use such techniques and look at the log by using "show log" in the logic debugger I see no reference to the SQL I used. It is as if the generated SQL has not made use of my functions. Instead all I seee are the extract statements from the three fact tables. Is this normal? Is there a way to see what SQL is really being generated and run?
At the moment it seems my only option is to make changes, try running it and hope I get an output. If no records are written I can't be sure whether it is because embedding SQL function is not supported or because I have made some other error.

Answer 1

No, the "BPC SQL" script logic doesn't allow for this extensive use of real SQL within the scripting syntax. As a concept, it's best to think of "BPC SQL" script logic as, "this unique BPC logic syntax will generate real SQL code when it's executed."
There's very little real SQL that you can use within the syntax itself, and definitely not within the WHEN or IF statements.  Nothing like cast, convert, substring, etc. (Except you CAN use these, a little bit, in a *SELECT statement. But I don't see how that will solve your current problem.)
Plus, when you consider how the logic engine processes a set of data, it's helpful to think of it in terms of selects & reading through a recordset. So in that regard, a SQL background can be helpful, in understanding the concepts. (Sort of helpful, except when it confuses you, or frustrates you since you don't have all the power you want.)
Anyway, to solve your problem, you might be able to restate the problem, and then use something like this code, which is valid syntax:
*WHEN TIME.TIMEID
*IS >= VERSION.FirstPlanMonthTimeID
In this case, FirstPlanMonthTimeID is set up in the version dimension as, for example, 20090400 (representing 2009.APR). This timeID is set by BPC automatically when processing the time dimension, and I need to ensure that my Version property value is set to match it.
A key point is that in BPC fact tables, the time dimension is stored as TIMEID (not ID, unlike all the other dimensions), and can be used for comparative evaluation in script logic WHEN/IF. The comparison property needs to be stored as an 8-digit integer value. If your time dimension has days in it (along with months), check the TIMEID after processing, and you should see the pattern for assigning values to TIMEID for days and months, etc.
Normally, TIMEID is assigned pretty sensible and stable values. If it doesn't meet your logic requirements, you can create another property (be careful of USERTIMEID, since that has a specific purpose in the system which I've never fully understood) and assign that whatever (integer) values make sense.