Josh Berkus escreveu:
All,
I was discussing WITH RECURSIVE the other day, and realized that one thing
which we're not getting with this patch is a simplest-case simple syntax
which 75% of users are looking for. You know, the ones with simple
proximity trees who just want to find all children of one parent.
Would it be a worth it for us to implement a non-standard simple syntax
sugar on top of WITH RECURSIVE? Or, at least, something like
CONNECT_BY()
Yes Josh,
I was discussing WITH RECURSIVE with some students that I'm teaching and
they ask me exactly this:
"Why not use a syntax like...
SELECT level, lpad(' ', level*4) || last_name as last_name
FROM employee
START WITH employee_id = 10
CONNECT BY PRIOR employee_id = manager_id;
... that is rewrite (or aliased) in:
WITH RECURSIVE employee_rec(level, employee_id, last_name) AS
(SELECT 1, employee_id, last_name)
FROM employee
WHERE employee_id = 10
UNION ALL
SELECT employee_rec.level + 1, emp.employee_id, emp.last_name
FROM employee as emp, employee_rec
WHERE employee_rec.employee_id = emp.manager_id)
SELECT level, lpad(' ', level*4) || last_name FROM employee_rec;" ?
In my opnion, it will be more simple to understand too.
--
[]s
Dickson S. Guedes
Administrador de Banco de Dados
Projeto Colmeia - Florianópolis, SC
(48) 3322-1185, ramal: 26
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