Insert ordinal number - mysql

Question

MySQL 5.7
Consider the following sample data:
CREATE TABLE catalog_product_entity_media_gallery (
`value` VARCHAR(24),
`entity_id` INTEGER
);
INSERT INTO catalog_product_entity_media_gallery
(`value`, `entity_id`)
VALUES
('a01-some-item-p1-png.png', '1'),
('a01-some-item-p2-png.png', '1'),
('a01-some-item-d1-png.png', '1'),
('a01-some-item-d5-png.png', '1'),
('another-transparent.png', '2'),
('another-back.png', '2'),
('another-front.png', '2'),
('another-side.png', '2');
CREATE TABLE catalog_product_entity (
`entity_id` INTEGER,
`sku` VARCHAR(3)
);
INSERT INTO catalog_product_entity
(`entity_id`, `sku`)
VALUES
('1', 'a01'),
('2', 'b22');
CREATE TABLE catalog_product_entity_varchar (
`attribute_id` INTEGER,
`value` VARCHAR(24)
);
INSERT INTO catalog_product_entity_varchar
(`attribute_id`, `value`)
VALUES
('85', 'a01-some-item-p1-png.png'),
('85', 'another-transparent.png');
DB Fiddle of same: https://www.db-fiddle.com/f/7fAx1waY3TwjR34PanBkkv/0
With the query below, I get the following result:
select
a.value as 'original_file_name',
b.sku,
if(isnull(c.attribute_id), 0, 1) as 'is_default',
concat(sku, '_', if(isnull(c.attribute_id), concat('slideshow_', 'x'), 'default_1'), '.', substring_index(a.value, "." , -1)) as 'new_file_name'
from catalog_product_entity_media_gallery a
join catalog_product_entity b on b.entity_id = a.entity_id
left join catalog_product_entity_varchar c on c.attribute_id = 85 and c.value = a.value
order by sku, is_default desc;
+--------------------------+-----+------------+---------------------+
| original_file_name | sku | is_default | new_file_name |
+--------------------------+-----+------------+---------------------+
| a01-some-item-p1-png.png | a01 | 1 | a01_default_1.png |
| a01-some-item-p2-png.png | a01 | 0 | a01_slideshow_x.png |
| a01-some-item-d1-png.png | a01 | 0 | a01_slideshow_x.png |
| a01-some-item-d5-png.png | a01 | 0 | a01_slideshow_x.png |
| another-transparent.png | b22 | 1 | b22_default_1.png |
| another-back.png | b22 | 0 | b22_slideshow_x.png |
| another-front.png | b22 | 0 | b22_slideshow_x.png |
| another-side.png | b22 | 0 | b22_slideshow_x.png |
+--------------------------+-----+------------+---------------------+
In the new_file_name column, I want to insert an ordinal number in place of x. It should start at 1 for every new sku.
Wanted result:
a01_default_1.png
a01_slideshow_1.png
a01_slideshow_2.png
a01_slideshow_3.png
b22_default_1.png
b22_slideshow_1.png
b22_slideshow_2.png
b22_slideshow_3.png

Answer 1

Kindly try it
;with cte as (
select a.*,ROW_NUMBER() over (partition by new_file_name order by ID) as ROWNUMBER
from catalog_product_entity_media_gallery a
)
select concat(a.new_file_name,'_',ROWNUMBER) from cte

Answer 2

Using a variable that holds a number that increments for every row.
When is_default = 1, the number gets reset.
drop temporary table if exists pictures;
create temporary table pictures
select
a.entity_id,
a.value as original_file_name,
b.sku as sku,
if(isnull(d.attribute_id), 0, 1) as is_default,
substring_index(a.value, "." , -1) as file_extension
from catalog_product_entity_media_gallery a
join catalog_product_entity b on b.entity_id = a.entity_id
left join catalog_product_entity_varchar d on d.attribute_id = 85 and d.value = a.value
order by sku, is_default desc;
set #number = 0;
select
original_file_name,
sku,
is_default,
case
when
is_default = 0
then
#number := #number + 1
else #number := 0
end as number,
concat(sku, '_', if(is_default, 'default_1', concat('slideshow_', #number)), '.', file_extension) as new_file_name
from pictures;