日付の比較

SQLでのレポーティング

Tyler Pernes

Learning & Development Consultant

解くべき質問

先月 vs 前月？
7日ローリング？

original_table
+------------+----------+
| date       | revenue  |
|------------+----------|
| 2018-01-01 | 400      |
| 2018-01-02 | 380      |
| 2018-01-03 | 625      |
+------------+----------+

月次比較（MoM）

LAG(value, offset) は現在行より前の offset 行の value を返します。
LEAD(value, offset) は現在行より後の offset 行の value を返します。

月次比較（MoM）

手順1: 月次の売上を表示

SELECT
    DATE_PART('month',date) AS month,
    SUM(revenue) as current_rev
FROM original_table
GROUP BY month;

手順2: 前月の売上

SELECT
    DATE_PART('month',date) AS month,
    SUM(revenue) as current_rev,
    LAG(SUM(revenue)) OVER (ORDER BY DATE_PART('month',date)) AS prev_rev
FROM original_table
GROUP BY month;

月次比較（MoM）

手順3: 変化率を計算

SELECT
    DATE_PART('month',date) AS month,
    SUM(revenue) as current_rev,
    LAG(SUM(revenue)) OVER (ORDER BY DATE_PART('month',date)) AS prev_rev,
    SUM(revenue)
    /
    LAG(SUM(revenue)) OVER (ORDER BY DATE_PART('month',date))-1 AS perc_change
FROM original_table
GROUP BY month;

月次比較（MoM）

手順3: 変化率を計算

+--------+--------------+-----------+--------------+
| month  | current_rev  | prev_rev  | perc_change  |
|--------+--------------+-----------+--------------|
| 01     | 15000        | null      | null         |
| 02     | 14000        | 15000     | -.06         |
| 03     | 21000        | 14000     | .50          |
+--------+--------------+-----------+--------------+

ローリング計算

7行のみを対象

新しい句: ROWS BETWEEN

SUM(value) OVER (ORDER BY value ROWS BETWEEN N PRECEDING AND CURRENT ROW)

ローリング計算

ローリング合計のクエリ

SELECT 
    date,
    SUM(SUM(revenue)) OVER 
    (ORDER BY date ROWS BETWEEN 6 PRECEDING AND CURRENT ROW) AS weekly_revenue
FROM original_table
GROUP BY date;

新しいテーブル: web_data

web_data
+------------+-------------+--------+
| date       | country_id  | view   |
|------------+-------------+--------|
| 2018-01-01 | 1           | 24313  |
| 2018-01-01 | 2           | 3768   |
| 2018-01-01 | 3           | 26817  |
+------------+-------------+--------+

Ayo berlatih!

SQLでのレポーティング