Question

我在APEX中有一个查询，该查询基于顶点中项目的值使用where子句条件。如果日期是null，那么我想显示表中的所有记录，如果日期不是null，我想基于该值添加where条件。我怎样才能做到这一点？

如果P2_SELECT_DATE不为null，我想添加以下两个条件：

select * from HR_DATA
where 
     :P2_SELECT_DATE between  person_eff_start_date and person_eff_end_date
 and :P2_SELECT_DATE between nvl(assign_eff_start_date,sysdate-1) and nvl(assign_eff_end_date, sysdate+1)

如果P2_SELECT_DATE为null，那么我根本就不想在where子句中拥有这些条件。

Answer 1

您可以这样做：

select * from HR_DATA
where (:P2_SELECT_DATE is null
      or (:P2_SELECT_DATE between person_eff_start_date and person_eff_end_date
         and :P2_SELECT_DATE between nvl(assign_eff_start_date,sysdate-1) 
                                 and nvl(assign_eff_end_date, sysdate+1)
      )

有时候，如果有很多可选的过滤器，动态创建查询会更有效：

declare
    q long;
begin    
    q := 'select * from HR_DATA where 1=1';

    if :P2_SELECT_DATE is null then
       q := q || ' and :P2_SELECT_DATE between person_eff_start_date and person_eff_end_date'
              || ' and :P2_SELECT_DATE between nvl(assign_eff_start_date,sysdate-1)'
              || ' and nvl(assign_eff_end_date, sysdate+1);
    end if;
    return q;
end;

“其中1 = 1”只是一个技巧，因此任何有条件附加的过滤器总是以“和”开头。

Oracle SQL查询中的条件where子句

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