oracle_to_pythonize.sql

WITH

rs as (
	select
		instr(play_string,',',1,6) as comma_position
		, play_string
	from mytable
	where substr(play_string,1,4)='play'
)

,

rs2 as (
	select
		substr(play_string,1,comma_position-2) as prefix_parse
		, substr(play_string,comma_position-1,1)as replace_parse
		, substr(play_string,comma_position) as suffix_parse
		, rs.*
	from rs
)

select
	play_string
	, prefix_parse || 'X' || suffix_parse as new_play_string

from rs2
where replace_parse in ('D', 'E')
;