mysql delimit and search column data - mysql

Question

MySQL version = 5.7.29
I want to do a MySQL search on a column which has delimited data. For example:
'field_black:1, field_white:2, field1_black:5, field_green:3'
I want a function which takes input the color and returns only the delimited values which do not have the input color.
func(input, color, delimiter)
func('field_black:1, field_white:2, field1_black:5, field1_green:3', 'black', ',') = 'field_white:2, field1_green:3'
This is pretty easy to implement in python using string split on delimiter and returning result set where the color is not in the given input.
def func(inp, col, delim):
inp = inp.split(delim)
res = []
for data in inp:
if col not in data:
res.append(data)
return (','.join(res))
Can anyone help me with an equivalent implementation in MySQL.
Thank you for the help!

Answer 1

CREATE FUNCTION func (input TEXT, color TEXT, delimiter CHAR(1))
RETURNS TEXT
DETERMINISTIC
BEGIN
DECLARE piece TEXT;
DECLARE result TEXT DEFAULT '';
/* SET color = CONCAT('field_', color); */ /* uncomment if needed */
REPEAT
SET piece = SUBSTRING_INDEX(input, delimiter, 1);
SET input = SUBSTRING(input FROM 2 + LENGTH(piece) FOR LENGTH(input));
IF NOT LOCATE(color, piece) THEN
SET result = CONCAT(result, delimiter, TRIM(piece));
END IF;
UNTIL input = ''
END REPEAT;
RETURN TRIM(BOTH delimiter FROM result);
END
fiddle
PS. Of course you may use multi-char delimiter if needed - alter input parameter type simply.

Answer 2

Just cracked this after a few iterations due to unfamiliarity with MySQL syntax. This is unnecessarily complicated though.
Answer by Akina is more simple and elegant: mysql delimit and search column data
CREATE FUNCTION `new_function`(input longtext, col TEXT, delim CHAR(1)) RETURNS longtext CHARSET utf8
DETERMINISTIC
BEGIN
declare result longtext default '';
declare piece longtext default '';
declare inptext longtext default '';
set inptext = input;
while (substring_index(inptext,delim,1) = '') = 0 DO
set piece = substring_index(inptext,delim,1);
IF NOT LOCATE(col, piece) THEN
set result = concat(result, piece, delim);
END IF;
set inptext = substr(inptext, length(SUBSTRING_INDEX(inptext, '|', 1) ) + 2);
END WHILE;
set result = left(result, length(result) -1);
RETURN result;
END