ListAgg and Split – Grouping, Aggregating and Dividing Again

Almost everybody working with SQL knows the GROUP BY specification for accumulating identical information. Those queries are quite often combined with aggregate functions such as SUM() or AVG().
 
With the multi-dimensional grouping it is possible to also add all kinds of sub-totals as well as a grand total to the queries.
In composition with CASE clauses it is possible to accumulate information and return the data in different columns, for example monthly or quarterly sales per customer. Pivot tables can be easily created … as long as the number of output columns is fixed.
Sometimes, however, we have to accumulate information that is located in multiple rows in a single row, for example all items in an order.
 
Unfortunately, the number of output columns (i.e. Items) may differ. However, with the LISTAGG aggregate function a string containing the different information separated by a comma (or any individual separation string) can be built.
 
As far as good … but how to split a string with multiple information separated by a comma or any other individual separation string? No problem with the SPLIT service! … in composition with other services even *.csv files located in the IFS can be decomposed