Error in WITH RECURSIVE while troubleshooting hacker rank - mysql

Question

Summary HackerRank Problem
(1) Draw Triangle 1
P(5) :
* * * * *
* * * *
* * *
* *
*
This is example and i have to make this P(20)
WITH RECURSIVE stars (n,star) AS(
SELECT 39,LEFT('* * * * * * * * * * * * * * * * * * * *',39)
UNION ALL
SELECT n-2,LEFT('* * * * * * * * * * * * * * * * * * * *',n-2)
FROM stars
WHERE n>1
)
SELECT star
FROM stars
I solved question of Draw the Triangle 1 in this way.
(2) Draw Triangle 2
P(5):
*
* *
* * *
* * * *
* * * * *
This is example and i have to make this P(20)
However, this does not work in Draw THE Triangle 2
WITH RECURSIVE stars (n,star) AS(
SELECT 1, LEFT('* * * * * * * * * * * * * * * * * * * *',1)
UNION ALL
SELECT n+2, LEFT('* * * * * * * * * * * * * * * * * * * *',n+2)
FROM stars
WHERE n<38
)
SELECT star
FROM stars
WITH RECURSIVE stars (n,star) AS(
SELECT 1,'*'
UNION ALL
SELECT n+1, CONCAT(star,' *')
FROM stars
WHERE n<20
)
SELECT star
FROM stars
I tried using LEFT() by changing the number just like Triange 1, but the HackerRank site showed a message like 'ERROR 1406 (22001) at line 1: Data too long for column 'star' at row 1' In my personal mysql, I only got OK, but I couldn't see the result table.
If the data is too long and it is an error, shouldn't I meet the same error in the first problem?
Is there something I don't know ?

Answer 1

Take a good look at outputs of queries for "triangle 1" and "triangle 2".
What is the difference? That's right, rows for the "triangle 2" query are in reverse order.
Which value in the query for "triangle 1" defines the order of rows? That's right, it's n.
How can I modify the query for "triangle 1" so that it outputs rows in reverse order? That's right, since the value of n in the first row is 39 and the last one is 1 (the rows are ordered by n in descending order), just reverse rows order by adding ORDER BY n.
So the query for "triangle2" should look like
WITH RECURSIVE stars(n, star) AS(
SELECT 39, LEFT('* * * * * * * * * * * * * * * * * * * *', 39)
UNION ALL
SELECT n-2, LEFT('* * * * * * * * * * * * * * * * * * * *', n-2)
FROM stars
WHERE n > 1
)
SELECT star
FROM stars
ORDER BY n
Just check it