在where子句中使用if-else / decode

Question

我有一个具有多个条件的游标，用于检索一组数据。 我最近在其中添加了日期条件，以检索用户输入的特定日期之间的数据，如下所示：

cursor c1
  is
     select  t.*
         from (select v.*, dense_rank () over (order by created desc)
                                                                  as rank
                 from test.table_v2 v
                where some condition
                and some condition
                  and some condition
                  and some condition
                  and some condition
                  and some condition
                 and ((ended) between to_date(sd,'mm/dd/rrrr')
                                  and to_date(sd,'mm/dd/rrrr')+3
                     or ended like decode(sd,null,'%')) --new condition
                 and some condition
                ) t
        where rank < rmax+1
     order by ended desc;

此处rmax = 1000

我需要在where子句中添加一个条件，以便当sd（用户输入的日期）为null时，行被限制为1000，而当其为非null时，则不应考虑行限制。

我不确定解码是否可以在where子句中使用。 有什么办法吗？

Answer 1

只需添加or sd is [not] null

select  t.*
     from (select v.*, dense_rank () over (order by created desc)
                                                              as rank
             from test.table_v2 v
            where some condition
            and some condition
              and some condition
              and some condition
              and some condition
              and some condition
             and (ended between to_date(sd,'mm/dd/rrrr')
                            and to_date(sd,'mm/dd/rrrr')+3
                 or sd is null) --new condition
             and some condition
            ) t
    where rank < rmax+1 or sd is not null