Need guidance in removing + in the result using REGEXP - snowflake-cloud-data-platform

Question

SELECT ID,
lower(LISTAGG(DISTINCT COL_A, ',') WITHIN GROUP(ORDER BY COL_A)) AS COL_1
FROM table_1
WHERE date = '2022-02-02'
GROUP BY ID
ID
COL_1
12345
abc,+bda,+beach,relax
23456
unknown_user,+unknown_member,+others_to_denote
When I run the above query, I'm getting results like mentioned above. I want the + symbol to be removed from the results. Is it possible to use REGEXP in this case?

Answer 1

So you should do your cleaning prior to the LIST_AGG because currently you can have abc in your output many times:
SELECT
column1 AS ID
,LISTAGG(DISTINCT lower(column2), ',') WITHIN GROUP(ORDER BY lower(column2)) AS COL_1_a
,lower(LISTAGG(DISTINCT column2, ',') WITHIN GROUP(ORDER BY column2)) AS COL_1_b
,replace(COL_1_b,'+')
FROM VALUES
(12345, 'abc'),
(12345, 'ABC'),
(12345, '+ABC'),
(12345, '+ABc'),
(12345, '+AbC'),
(12345, '+bda')
GROUP BY ID;
gives:
ID
COL_1_A
COL_1_B
REPLACE(COL_1_B,'+')
12345
+abc,+bda,abc
+abc,+abc,+abc,+bda,abc,abc
abc,abc,abc,bda,abc,abc
thus with a layer of "cleaning"
SELECT
ID
,LISTAGG(DISTINCT col2_cleaned, ',') WITHIN GROUP(ORDER BY col2_cleaned) AS COL_1
FROM (
SELECT column1 as id,
replace(lower(column2),'+') AS col2_cleaned
FROM (
VALUES
(12345, 'abc'),
(12345, 'ABC'),
(12345, '+ABC'),
(12345, '+ABc'),
(12345, '+AbC'),
(12345, '+bda')
)
)
GROUP BY ID;
more sensible results are produced:
ID
COL_1
12345
abc,bda
Other Cleaning points:
Do you really want all + tokens removed, sometimes it is just tokens at the beginning or the end that we want to remove, thus the replace can remove too much:
SELECT column1 as orig
,replace(lower(column1),'+') AS all_cleaned
,ltrim(lower(column1),'+') AS lt_cleaned
,rtrim(lower(column1),'+') AS rt_cleaned
,trim(lower(column1),'+') AS t_cleaned
FROM VALUES
('abc'),
('ABC'),
('+A+BC'),
('+AB+c+'),
('+AbC+')
;
ORIG
ALL_CLEANED
LT_CLEANED
RT_CLEANED
T_CLEANED
abc
abc
abc
abc
abc
ABC
abc
abc
abc
abc
+A+BC
abc
a+bc
+a+bc
a+bc
+AB+c+
abc
ab+c+
+ab+c
ab+c
+AbC+
abc
abc+
+abc
abc
But you can also use REGEXP_REPLACE if you want to remove upto 2 + from the beginning but not more:
,regexp_replace(lower(column1), '\\+{1,2}','',1,1,'e')

Answer 2

if you just want to remove +, then you can use REPLACE
SELECT ID,COL_1, replace(col_1,'+') FROM VALUES
('12345', 'abc,+bda,+beach,relax')
,('23456','unknown_user,+unknown_member,+others_to_denote') as tab(ID,COL_1)