基本的な集計関数

SQL Serverで学ぶ時系列分析

Maham Faisal Khan

Senior Data Science Content Developer

主要な集計関数

カウント

COUNT()

COUNT_BIG()

COUNT(DISTINCT)

その他の集計

SUM()

MIN()

MAX()

COUNT() で数えられるもの

行数

COUNT(*)

COUNT(1)

COUNT(1/0)

NULL 以外の値

COUNT(d.YR)

COUNT(NULLIF(d.YR, 1990))

DISTINCT のカウント

SELECT
    COUNT(DISTINCT c.CalendarYear) AS Years,
    COUNT(DISTINCT NULLIF(c.CalendarYear, 2010)) AS Y2
FROM dbo.Calendar c;

Years	Y2
50	49

CASE で集計を絞り込む

SELECT
    MAX(CASE WHEN ir.IncidentTypeID = 1
            THEN ir.IncidentDate
            ELSE NULL
        END) AS I1,
    MAX(CASE WHEN ir.IncidentTypeID = 2
            THEN ir.IncidentDate
            ELSE NULL
        END) AS I2,
FROM dbo.IncidentRollup ir;

I1	I2
2020-06-30	2020-06-29

Passons à la pratique !

SQL Serverで学ぶ時系列分析