如何基于时间戳从单列中检索日期

Question

我每天将数据插入数据库中。我需要基于时间戳检索单列数据。我需要根据时间戳显示今天用法和昨天用法。

我的实际表格

name       usage          timestamp
prod        200     2019-01-08 09:22:53.364366
Test        100     2019-01-08 09:22:53.364366
qality      50      2019-01-08 09:22:53.364366
prod        270     2019-01-09 08:22:53.364366
Test        300     2019-01-09 08:22:53.364366
qality      90      2019-01-09 08:22:53.364366

Expecting output:

name       usage(yesterday)     usage(Today)         timestamp
prod        200                  270                2019-01-09 08:22:53.364366
Test        100                  300                2019-01-09 08:22:53.364366
qality      50                   90                 2019-01-09 08:22:53.364366

Answer 1

尝试按名称进行汇总，然后检查时间戳记：

SELECT
    name,
    MAX(CASE WHEN timestamp::date = NOW()::date - INTERVAL '1 DAY'
             THEN usage END) AS u_yesterday,
    MAX(CASE WHEN timestamp::date = NOW()::date
             THEN usage END) AS u_today,
    MAX(timestamp) AS timestamp
FROM yourTable
GROUP BY
    name;