Recursively replace string using a CTE - sql-server

Question

I am having lookup_table as following:-
| id | Val |
+------+-----+
| 1 | A |
| 11 | B |
| 111 | C |
| 1111 | D |
I am creating words using the values from lookup_table like $id! and saving it into another table.
example : bad - $11!$1!$1111!
So my data_table will be something like,
| expression |
+-----------------+
| $111!$1!$11! | -- cab
| $1111!$1!$1111! | -- dad
| $11!$1!$1111! | -- bad
I want to reverse-build the word from the data_table.
What I've tried: used CHARINDEX on $ and ! to get the first id from expression and tried to replace it with matching val from look_up table recursively using CTE. I was not getting the exact result I was getting, but with some filetring, I got something close.
The query I've tried :
;WITH cte AS
(SELECT replace(expression,'$' + CONVERT(varchar(10),id) + '!' ,val) AS 'expression',
cnt =1
FROM data_table
JOIN lookup_table ON id =
SUBSTRING(
SUBSTRING(expression, CHARINDEX('$', expression) + 1, LEN(expression) - CHARINDEX('$', expression)), 1, CHARINDEX('!', expression) - 2)
UNION ALL
SELECT replace(expression,'$' + CONVERT(varchar(10),id) + '!' ,val) AS 'expression' ,
cnt = cnt +1
FROM cte
JOIN lookup_table ON id =
SUBSTRING(
SUBSTRING(expression, CHARINDEX('$', expression) + 1, LEN(expression) - CHARINDEX('$', expression)), 1, CHARINDEX('!', expression) - (cnt +2))
WHERE CHARINDEX('$', expression) > 0 )
SELECT expression
FROM cte
WHERE CHARINDEX('$', expression) = 0
Current output :
| expression |
+------------+
| DAD |
| CAB |
Expected output:
| expression |
+------------+
| DAD |
| CAB |
| BAD |
fiddle
What am I doing wrong?
Edit: There was a typo in the data setup in fiddler. d in bad was having five 1s instead of four. Thanks, DarkRob for pointing it out.

Answer 1

You may try this. Instead of using recursive cte you may use multiple cte to create your expression. Since sql already introduced this string_split function to convert your row cell into rows on particular delimeter, this will make our work lot easier.
First we convert each cell value into individual rows. Further we can easily get our expression word by using inner join with lookup table. At the last using stuff we'll again get our string as we need.
;WITH CTE AS (
SELECT ROW_NUMBER() OVER (ORDER BY EXPRESSION) AS SLNO, * FROM data_table
),
CT AS (
SELECT *, REPLACE(VALUE,'$','') AS NEWVAL
FROM CTE CROSS APPLY string_split(EXPRESSION,'!') WHERE VALUE <> ''
),
CTFINAL AS (
SELECT * FROM CT INNER JOIN lookup_table AS LT ON CT.NEWVAL=LT.id
)
--SELECT * FROM CTFINAL
SELECT DISTINCT SLNO,
STUFF( (SELECT '' + VAL + '' FROM CTFINAL AS CFF WHERE CFF.SLNO=CF.SLNO FOR XML PATH('')), 1,0,'') AS MYVAL
FROM CTFINAL AS CF