Question

How to make a request to group all the fields in one row?

Table:

id | type
---------
1  | 1
1  | 1
2  | 2
3  | 3
3  | 3

query:

select concat('id(', count(type), ')') from T group by id;

output:

id(2)
id(1)
id(2)

I want to get a string like: 'id(1)' = 2, 'id(2)' = 1, 'id(3)' = 2

Answer 1

If you do it in two stages. Make your id(n) = x records, then GROUP_CONCAT() them.

SELECT
  GROUP_CONCAT(id_count SEPARATOR ', ')
FROM
  (SELECT CONCAT('id(', id, ') = ', count(type)) id_count FROM T GROUP BY id) data

But do note that this is often a sign of a SQL Anti-Pattern.

It is normally recommended to not compress multiple values into a single value. And it is normally recommended to keep presentation and data layer separate.