윈도우에서 집계 함수 사용

SQL Server에서의 시계열 분석

Maham Faisal Khan

Senior Data Science Content Developer

순위 함수

`ROW_NUMBER()`

1부터 시작하는 고유 오름차순 정수.

`RANK()`

1부터 시작하는 오름차순 정수. 동점 가능. 숫자 건너뜀 가능.

`DENSE_RANK()`

1부터 시작하는 오름차순 정수. 동점 가능. 숫자 건너뛰지 않음.

RunsScored
8
7
7
6
6
3

행 번호 계산

SELECT
    s.RunsScored,
    ROW_NUMBER() OVER (
      ORDER BY s.RunsScored DESC
    ) AS rn
FROM dbo.Scores s
ORDER BY
    s.RunsScored DESC;

RunsScored	rn
8	1
7	2
7	3
6	4
6	5
3	6

RANK와 DENSE_RANK 계산

SELECT
    s.RunsScored,
    RANK() OVER (
      ORDER BY s.RunsScored DESC
    ) AS rk,
    DENSE_RANK() OVER (
      ORDER BY s.RunsScored DESC
    ) AS dr
FROM dbo.Scores s
ORDER BY
    s.RunsScored DESC;

RunsScored	rk	dr
8	1	1
7	2	2
7	2	2
6	4	3
6	4	3
3	6	4

파티션

SELECT
    s.Team,
    s.RunsScored,
    ROW_NUMBER() OVER (
      PARTITION BY s.Team
      ORDER BY s.RunsScored DESC
    ) AS rn
FROM dbo.Scores s
ORDER BY
    s.RunsScored DESC;

Team	RunsScored	rn
AZ	8	1
AZ	6	2
AZ	3	3
FLA	7	1
FLA	7	2
FLA	6	3

집계 함수

SELECT
    s.Team,
    s.RunsScored,
    MAX(s.RunsScored) OVER (
      PARTITION BY s.Team
    ) AS MaxRuns
FROM dbo.Scores s
ORDER BY
    s.RunsScored DESC;

Team	RunsScored	MaxRuns
AZ	8	8
AZ	6	8
AZ	3	8
FLA	7	7
FLA	7	7
FLA	6	7

빈 윈도우의 집계

SELECT
    s.Team,
    s.RunsScored,
    MAX(s.RunsScored) OVER() AS MaxRuns
FROM dbo.Scores s
ORDER BY
    s.RunsScored DESC;

Team	RunsScored	MaxRuns
AZ	8	8
AZ	6	8
AZ	3	8
FLA	7	8
FLA	7	8
FLA	6	8

연습해 봅시다!

SQL Server에서의 시계열 분석