sql - PostgreSQL WITH 查询已选择的表

Question

我使用 PostgreSQL WITH https://www.postgresql.org/docs/current/static/queries-with.html .我可以运行非常复杂的查询，但我可以使用已经排序的数据吗？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

谢谢

更新

我在 Ruby on Rails 中使用此查询的所有问题。我使用这样的关联:

@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

WITH QUERIES 上的每个查询都被视为临时表。您可以根据需要提出任意数量的查询:

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;