如何计算两个Oracle时间戳之间的毫秒差异？

确定 Oracle 时间戳中的毫秒差异

使用 Oracle 时间戳通常需要计算两个值之间的精确时间差。虽然秒或分钟的差异很常见，但在特定应用中计算精确到毫秒的差异可能至关重要。

方法

EXTRACT 函数提供了一个解决方案。 它从 INTERVAL DAY TO SECOND 值中提取组件 - 减去两个时间戳的结果。

此初始查询提取日、小时、分钟和秒组成部分：

<code class="language-sql">SELECT EXTRACT(DAY FROM diff) AS days,
       EXTRACT(HOUR FROM diff) AS hours,
       EXTRACT(MINUTE FROM diff) AS minutes,
       EXTRACT(SECOND FROM diff) AS seconds
FROM (SELECT SYSTIMESTAMP - TO_TIMESTAMP('2012-07-23', 'YYYY-MM-DD') AS diff
      FROM DUAL);</code>

要获取总毫秒数，请转换这些分量并求和：

<code class="language-sql">SELECT EXTRACT(DAY FROM diff) * 24 * 60 * 60 * 1000 +
       EXTRACT(HOUR FROM diff) * 60 * 60 * 1000 +
       EXTRACT(MINUTE FROM diff) * 60 * 1000 +
       ROUND(EXTRACT(SECOND FROM diff) * 1000) AS total_milliseconds
FROM (SELECT SYSTIMESTAMP - TO_TIMESTAMP('2012-07-23', 'YYYY-MM-DD') AS diff
      FROM DUAL);</code>

重要提示： ROUND 函数确保秒以毫秒为单位准确表示。

虽然可以计算总毫秒数，但保留 INTERVAL DAY TO SECOND 结果或为每个时间单位使用单独的列通常更实用。 然而，这种方法可以在需要时提供精确的毫秒计算。

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