https://dev.mysql.com/doc/refman/8.0/en/window-functions-named-windows.html
MySQL :: MySQL 8.0 Reference Manual :: 14.20.4 Named Windows
Windows can be defined and given names by which to refer to them in OVER clauses. To do this, use a WINDOW clause. If present in a query, the WINDOW clause falls between the positions of the HAVING and ORDER BY clauses, and has this syntax: WINDOW window_n
dev.mysql.com
https://dev.mysql.com/doc/refman/8.0/en/window-functions-frames.html
MySQL :: MySQL 8.0 Reference Manual :: 14.20.3 Window Function Frame Specification
14.20.3 Window Function Frame Specification The definition of a window used with a window function can include a frame clause. A frame is a subset of the current partition and the frame clause specifies how to define the subset. Frames are determined with
dev.mysql.com
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예시
SELECT time_at
, column1
, RANK() OVER (ORDER BY column1 DESC) AS rk
, DENSE_RANK() OVER (ORDER BY column1 DESC) AS dense_rk
, ROW_NUMBER() OVER (ORDER BY column1 DESC) AS row_n
FROM table1
ORDER BY rk이 쿼리에서 중복적으로 윈도우 함수를 호출하고 있다 .
이 중복되는 부분을 WINDOW 윈도우이름 AS (윈도우스펙) 형식으로 정의를 한 후 윈도우 이름을 호출하여 유용하게 사용할 수 있다!
SELECT time_at
, column1
, RANK() OVER wd AS rk
, DENSE_RANK() OVER wd AS dense_rk
, ROW_NUMBER() OVER wd AS row_n
FROM table1
-- 윈도우 형식 호출하기 위한 형식을 작성--
WINDOW wd AS (ORDER BY column1 DESC)
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