PostgreSQL WITH查詢已經選定的表

Question

我使用PostgreSQL WITHhttps://www.postgresql.org/docs/current/static/queries-with.html。我可以運行相當複雜的查詢，但是我可以使用已排序的數據嗎？例如：

SELECT id, f_name, l_name, email FROM users 
WHERE f_name = 'BabyBoy' 

WITH i_need_do_thomething AS (
# and than use that filtered data 
) 
SELECT * FROM i_need_do_thomething 

感謝

UPDATE

，我在Ruby中使用此查詢on Rails的所有問題。我用聯想，如：

@laptop = Laptop.find(1) 
@laptop.user.do_custom_sql(HERE_WILL_BE_RAW_SQL) 

其中@laptop.user等於

SELECT id, f_name, l_name, email FROM users 
WHERE f_name = 'BabyBoy' 

Answer 1

上WITH QUERIES每個查詢都被視爲一個臨時表。您可以根據需要放置儘可能多的查詢：

WITH filtered_something AS (
    SELECT id, f_name, l_name, email FROM users WHERE f_name = 'BabyBoy' 
), i_need_do_something AS (
    SELECT * FROM filtered_something 
) 
SELECT * FROM i_need_do_something;