问题描述
请帮助我了解此 sql 语法。想要根据另一个表中每分钟的唯一值将 avr 值放入表一。 最佳/彼得
表 1
Activity,starttime,endtime
Dance,2010-01-01 15:00,2010-01-01 15:05
表 2
Activity,Minute,Value
Dance,50
Dance,2010-01-01 15:01,10
Dance,2010-01-01 15:02,2010-01-01 15:03,20
Dance,2010-01-01 15:04,10
想要的结果
Activity,endtime,avr Value
Dance,2010-01-01 15:05,20
解决方法
一种方法是相关子查询:
select t1.*,(select avg(t2.value)
from table2 t2
where t2.activity = t1.activity and
t2.minute >= t1.starttime and
t2.minute < t1.endtime
) as avg_value
from table1 t1;