Generate a number sequence grouped on a column/key in SAP BODS

Scenario: Create a sequence number grouped or based on another key/column value from the source result set. 

eg: consider the following data-set

Now in the target dataset/table, we require a new column which would sequentially assign a number starting from 1 for each student under a particular class. The result set then would look something like below, 

Now we have this new column (StudentSeqNbr) which sequentially numbers each student under a particular ClassId. The aim is to create such a sequential column using SAP BODS.

Solution: SAP BODS has an inbuilt function which will let you create such a sequence and can be mapped inside a Query transform.

Gen Rownum function in SAP BODS( Click to enlarge )

Using this function and the below syntax, a sequence can be created for the scenario above.

gen_row_num_by_group(ClassId)

Syntax:

gen_row_num_by_group(ColumnName)

UPDATE: The input should be sorted for this function to work properly to create a sequence.