<p>算术函数允许您对包含日期的列执行算术运算。</p>
<p>例如,您可以计算两个日期之间的差异、向日期中添加天数或从日期中减去天数。内置的日期算术函数包括<code>datediff</code>、<code>date_add</code>、<strong><a href="https://spark.apache.org/docs/1.6.2/api/java/org/apache/spark/sql/functions.html#date_sub(org.apache.spark.sql.Column,%20int)" rel="noreferrer">^{<cd3>}</a></strong>、<code>add_months</code>、<code>last_day</code>,
<code>next_day</code>,和<code>months_between</code>。</p>
<p>我们需要的是</p>
<blockquote>
<p>date_sub(timestamp startdate, int days), Purpose: Subtracts a specified number of days
from a TIMESTAMP value. The first argument can be a string, which is
automatically cast to TIMESTAMP if it uses the recognized format, as
described in TIMESTAMP Data Type. Return type: timestamp</p>
</blockquote>
<p>我们有</p>
<blockquote>
<p>current_timestamp() Purpose: Alias for the now() function. Return
type: timestamp</p>
</blockquote>
<p>你可以选择</p>
<pre><code>date_sub(CAST(current_timestamp() as DATE), 1)
</code></pre>
<p>见<a href="https://spark.apache.org/docs/1.6.2/api/java/org/apache/spark/sql/functions.html" rel="noreferrer">https://spark.apache.org/docs/1.6.2/api/java/org/apache/spark/sql/functions.html</a></p>