Using 'Listagg' function and 'Regular Expression' to REVERSE the value of a specific column in Oracle

Question

I have a table with below structure:

create table TBL_TEST
(
  col_id   NUMBER,
  col_name VARCHAR2(500)
)

Some example data :

col_id | col_name   
-----------------
  1    | aetnap        
  2    | elppa       
  3    | ananab     
 

What I want to do is to reverse the value of col_name column like this :

col_id | col_name   
-----------------
  1    | pantea
  2    | apple
  3    | banana

I used listagg and regexp_replace to write the query:

select col_id,
       listagg(val) within group(order by val_row desc) original_value
  from (select col_id,
               val,
               row_number() over(partition by col_id order by col_id) val_row
          from (select col_id, trim(column_value) val
                  from tbl_test,
                       xmltable(trim(trailing ',' from
                                     regexp_replace(col_name, '(.)', '"\1",')))))
 group by col_id;

The query above works fine and gives me the desired result, I want to know if there are better ways of writing the query cause two sub queries are used in the query above and I want to know whether there are better ways than using a sub query.

Thanks in advance

Answer 1

select col_id, reverse(col_name) as col_name from tbl_test;

    COL_ID COL_NAME  
---------- ----------
         1 pantea    
         2 apple     
         3 banana