Know this command?
I think it’s very useful, but not so often I see that in use… More about it:
It was introduced in Oracle 11g Release 2, as an analytic function to make the life easier fot the PLSQL Dev, specially when working to aggregate strings. The nice thing about this function is it also allows us to order the elements in the concatenated list. If you are using 11g Release 2 you should use this function for string aggregation.
In case WM_CONCAT is in use for this end, be aware that WM_CONCAT is an undocumented function and as such is not supported by Oracle for user applications (MOS Note ID 1336219.1). Also, WM_CONCAT has been removed from 12c onward, once it was completely replaced by LISTAGG.
More info and examples can be found here: https://oracle-base.com/articles/12c/listagg-function-enhancements-12cr2
Hope you enjoy it. Cheers!