如何计算2个字段，然后得到一个区别

Question

Select count(*) from column_alerts
Select count(*) from column_alerts where publish_datetime > (sysdate - (2/24/60))

显示column_alerts的差异 - （2分钟后添加的记录）

感谢

Answer 1

Select count(*) - sum(case when publish_datetime >(sysdate - (2/24/60)) then 1 else 0 end) from column_alerts