sql - 上个月的Oracle日期函数

Question

我在下面的日期被硬编码的查询。我的目标是删除已编码的日期；查询在运行时应提取上个月的数据。

select count(distinct switch_id)
  from xx_new.xx_cti_call_details@appsread.prd.com
 where dealer_name =  'XXXX'
   and TRUNC(CREATION_DATE) BETWEEN '01-AUG-2012' AND '31-AUG-2012'

我应该为此使用 sysdate-15函数吗？

Answer 1

稍微修改Ben的查询，

 select count(distinct switch_id)   
  from xx_new.xx_cti_call_details@appsread.prd.com  
 where dealer_name =  'XXXX'    
   and creation_date between add_months(trunc(sysdate,'mm'),-1) and last_day(add_months(trunc(sysdate,'mm'),-1))