How to generate a survey curve with SQL query - mysql

Question

I have a table with 2 columns WorkItem and LiveDays. For example
| WorkItem | LiveDays |
| A | 8 |
| B | 2 |
| C | 5 |
....
I would like to generate a survey data of the work item. Each item is normalized as starting from day 1 and ending to LiveDays, and value of nth day is how many workitems is still live (in process). For example
| Days | Counter | Comments |
| 1 | 3 | (A, B, C)|
| 2 | 3 | (A, B, C)|
| 3 | 2 | (A, C) |
| 4 | 2 | (A, C) |
| 5 | 2 | (A, C) |
| 6 | 1 | (A) |
| 7 | 1 | (A) |
| 8 | 1 | (A) |
Is it possible to use SQL query instead of inserting data into a new table with transaction?
Thanks

Answer 1

To show it can be done (it does after all answer your original question) here's your example reproduced using Db2 Developer-C 11.1 on dbfiddle.uk: (You did say there were several databases you could use, and this will no doubt serve to illustrate that different databases do things in different ways!). Note: additional MySQL solution further down.
CREATE TABLE surveydata AS (
WITH t1(workitem, livedays)
AS (VALUES ('A', 8), ('B', 2), ('C', 5)),
numbers(seq)
AS (VALUES (1)
UNION ALL
SELECT seq + 1
FROM numbers
WHERE seq < (SELECT MAX(livedays)
FROM t1)),
xdata(workitem, ndays)
AS (SELECT workitem,
seq
FROM t1,
numbers
WHERE seq <= livedays)
SELECT ndays AS "Days",
COUNT(*) AS "Counter",
'(' || LISTAGG(workitem, ', ') WITHIN GROUP (ORDER BY workitem) || ')' AS "Comments"
FROM xdata
GROUP BY ndays
) WITH DATA;
with the result of SELECT * FROM surveydata as below ==>
UPDATE: With a bit more fiddling, I've managed to get a solution using MySQL 8.0 as well:
WITH recursive t1(workitem, livedays)
AS (SELECT 'A', 8
UNION ALL SELECT 'B', 2
UNION ALL SELECT 'C', 5 ),
numbers(seq)
AS (SELECT 1 AS seq
UNION ALL
SELECT seq + 1
FROM numbers
WHERE seq < (SELECT MAX(livedays)
FROM t1)),
xdata(workitem, ndays)
AS (SELECT workitem,
seq
FROM t1,
numbers
WHERE seq <= livedays)
SELECT ndays AS "Days",
COUNT(*) AS "Counter" ,
CONCAT('(', GROUP_CONCAT(workitem ORDER BY workitem SEPARATOR ', '), ')') AS "Comments"
FROM xdata
GROUP BY ndays;