Add row number after splitting a string field - mysql

Question

I have a table that contains 2 fields:
ID: text
Suggestions: string (comma separated values)
I would like to make a select query that would return a new numbered rows representing each suggestion with its own number as shown in the original string
Example:
Note: this ranking must be guaranteed to be the same everytime I run the query..
Thanks

Answer 1

If Version of your DB is 8.0+, then with recursive cte as clause might be used as in the following select statement ( after needed DML's provided such as create table and insert statements ):
mysql> create table tab( ID int, suggestions varchar(25));
mysql> insert into tab values(1,'A,B,C');
mysql> insert into tab values(2,'D,E,F,G,H');
mysql> select q2.*,
row_number()
over
(partition by q2.id order by q2.suggestion) as number
from
(
select distinct
id,
substring_index(
substring_index(suggestions, ',', q1.nr),
',',
-1
) as suggestion
from tab
cross join
(with recursive cte as
(
select 1 as nr
union all
select 1+nr from cte where nr<10
)
select * from cte) q1
) q2;
+------+------------+--------+
| id | suggestion | number |
+------+------------+--------+
| 1 | A | 1 |
| 1 | B | 2 |
| 1 | C | 3 |
| 2 | D | 1 |
| 2 | E | 2 |
| 2 | F | 3 |
| 2 | G | 4 |
| 2 | H | 5 |
+------+------------+--------+

Answer 2

Find here same problem is solved.
https://gist.github.com/avoidwork/3749973

Answer 3

I would suggest a series of subqueries:
select id, substring_index(suggestions, ',', 1) as suggestion, 1
from example
where suggestions is not null
union all
select id, substring_index(substring_index(suggestions, ',', 2), ',', -1) as suggestion, 2
from example
where suggestions like '%,%'
union all
select id, substring_index(substring_index(suggestions, ',', 3), ',', -1) as suggestion, 3
from example
where suggestions like '%,%,%'
union all
select id, substring_index(substring_index(suggestions, ',', 4), ',', -1) as suggestion, 4
from example
where suggestions like '%,%,%,%'
union all
select id, substring_index(substring_index(suggestions, ',', 5), ',', -1) as suggestion, 5
from example
where suggestions like '%,%,%,%,%';
This can easily be extended if you have more than 5 options per id.