MySQL 8.0

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CREATE TABLE test (id INT, txt VARCHAR(255));
INSERT INTO test VALUES
(1,'gruppo-1_text_1'),
(2,'gruppo-12_text_12'),
(3,'gruppo-_text_none'),
(4,'gruppo-44s_text_not_number'),
(5,'gruppo-555 _text_not_number_too'),
(6,'gruppo-1234567890_text_long'),
(6,'gruppo-0000000000_text_long_zerofill');
SELECT * FROM test;

Records: 7  Duplicates: 0  Warnings: 0




id
txt


1
gruppo-1_text_1

2
gruppo-12_text_12

3
gruppo-_text_none

4
gruppo-44s_text_not_number

5
gruppo-555 _text_not_number_too

6
gruppo-1234567890_text_long

6
gruppo-0000000000_text_long_zerofill


SELECT id, txt, SUBSTRING(txt FROM 1 + LOCATE('_', txt)), txt REGEXP '^gruppo-\\d+_.*'
FROM test


id
txt
SUBSTRING(txt FROM 1 + LOCATE('_', txt))
txt REGEXP '^gruppo-\d+_.*'


1
gruppo-1_text_1
text_1
1

2
gruppo-12_text_12
text_12
1

3
gruppo-_text_none
text_none
0

4
gruppo-44s_text_not_number
text_not_number
0

5
gruppo-555 _text_not_number_too
text_not_number_too
0

6
gruppo-1234567890_text_long
text_long
1

6
gruppo-0000000000_text_long_zerofill
text_long_zerofill
1


SELECT id, txt, SUBSTRING(txt FROM 1 + LOCATE('_', txt))
FROM test
WHERE txt REGEXP '^gruppo-\\d+_.*'


id
txt
SUBSTRING(txt FROM 1 + LOCATE('_', txt))


1
gruppo-1_text_1
text_1

2
gruppo-12_text_12
text_12

6
gruppo-1234567890_text_long
text_long

6
gruppo-0000000000_text_long_zerofill
text_long_zerofill

id	txt
1	gruppo-1_text_1
2	gruppo-12_text_12
3	gruppo-_text_none
4	gruppo-44s_text_not_number
5	gruppo-555 _text_not_number_too
6	gruppo-1234567890_text_long
6	gruppo-0000000000_text_long_zerofill

id	txt	SUBSTRING(txt FROM 1 + LOCATE('_', txt))	txt REGEXP '^gruppo-\d+_.*'
1	gruppo-1_text_1	text_1	1
2	gruppo-12_text_12	text_12	1
3	gruppo-_text_none	text_none	0
4	gruppo-44s_text_not_number	text_not_number	0
5	gruppo-555 _text_not_number_too	text_not_number_too	0
6	gruppo-1234567890_text_long	text_long	1
6	gruppo-0000000000_text_long_zerofill	text_long_zerofill	1