PostgreSQL WITH查询已经选定的表

Question

我使用PostgreSQL WITHhttps://www.postgresql.org/docs/current/static/queries-with.html。我可以运行相当复杂的查询，但是我可以使用已排序的数据吗？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 

感谢

UPDATE

，我在Ruby中使用此查询on Rails的所有问题。我用联想，如：

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

其中@laptop.user等于

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

Answer 1

上WITH QUERIES每个查询都被视为一个临时表。您可以根据需要放置尽可能多的查询：

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;