擅长:python、mysql、java
<p>在纯SQL中,您可以实现如下相同的效果(相应地指定日期):</p>
<pre><code>select product.name
, avg(case when product_assessment.record_date = <todays date> then product_assessment.score else 0 end) as today
, avg(case when product_assessment.record_date between <start date> and <end date> then product_assessment.score else 0 end) as wtd
, avg(case when product_assessment.record_date between <start date> and <end date> then product_assessment.score else 0 end) as mtd
, avg(case when product_assessment.record_date between <start date> and <end date> then product_assessment.score else 0 end) as ytd
from product, product_assessment
where product.id = product_assessment.product_id
group by product.name;
</code></pre>