sql求取变更次数方法_Oracle开发

sql求取变更次数方法求助
现在有表
ba_purchase
字段如下：
id，purchase_code 套餐编号，purchase_lowest_cost 套餐金额，date（每天都有记录），sp_code 企业编号
现在要计算，任意一段时间内，企业套餐变更的次数，变更的条件就是 pruchase_code不一样;
变更的企业个数，条件是在任意一段时间内，只要该企业有变更就计算；
求各位大侠帮忙啊！

------解决方案--------------------

SQL code

select count(1) from ba_purchasewhere date>=? and data<=?group by sp_codehaving count(purchase_code)>1
------解决方案--------------------
select count(distinct purchase_code)
 from ba_purchase
  where sp_code = 企业编号
  and date between 开始日期 and 截止日期;
   
select count(*)
 from (select *
         From ba_purchase
        where date between 开始日期 and 截止日期
        group by sp_code, purchase_code
       having count(*) > 1);