Question

I have an issue regarding an recursive count which works well in SQL server, but I can not make this work in mySQL.

In SQL Server I used to use:

SELECT
@Param= not_unique_id,
(Select Count(not unique id) FROM TABLE0 WHERE not_unique_id=@Param)
FROM Table0 WHERE .....

this will give me:
1 2
1 2
2 1
3 3
3 3
3 3

this will give me the number of id’s per current row id as parameter

In mySQL i do the same:

SELECT
Param=not_unique_id,

(returns NULL, SET is not allowed here)

(Select Count(not unique id) FROM TABLE0 WHERE not_unique_id=Param)
FROM Table0 WHERE .....

this will give me:
NULL NULL
NULL NULL
NULL NULL
NULL NULL
NULL NULL
NULL NULL

Alternatively, I tried with:
In mySQL i do the same:

SELECT
not_unique_id,
(Select Count(not unique id) FROM TABLE0 WHERE not_unique_id=not_unique_id)
FROM Table0 WHERE .....

this will give me:
1 3
1 3
2 3
3 3
3 3
3 3

this will give me the unique count of the whole record

any idea how to do this in mySQL?

Answer 1

For assigning a value in mysql don’t forget :=

SELECT @Param:=not_unique_id,
(
 SELECT Count(not_unique_id)
 FROM TABLE0
 WHERE not_unique_id=@Param
)
FROM Table0 WHERE .....

or

SELECT not_unique_id,
(
 SELECT Count(not_unique_id)
 FROM TABLE0
 WHERE not_unique_id=a.not_unique_id
)
FROM Table0 a WHERE .....