Question

我有一个顶点项目P_USERS，其值可以比下面的查询返回的行数高。

我有一个经典报告，其中包含以下查询：

  select 
       first_name,
       last_name
  from  accounts
  where account_role = 'Author'
  order by account_nr;

如果查询的总行数小于first_name = null {{的值，我希望将占位符行添加到查询（last_name = null，apex_item等）中1}}。

有关如何实现此目标的任何提示？也许使用P_USERS？

Answer 1

您可以尝试使用LEFT JOIN。

首先，创建一个数字列表，直到达到所需的限制，例如suggested here：

-- let's say you want 300 records
Select Rownum r From dual Connect By Rownum <= 300

然后，您可以使用它退出联接并保留空白记录：

SELECT C, R FROM  
  ( select rownum i, c from (select  'a' c from dual union all select 'b' from dual) )
, ( Select Rownum r From dual Connect By Rownum <= 300)
where i(+)= r order by r

上面的代码为您提供了一个以'a'，'b'开头，然后为null直到结尾的有序列表。

因此您可以根据自己的情况进行调整，以便：

SELECT F,L FROM  
  ( select rownum i, f, l from (
             select first_name f, last_name l 
               from  accounts where account_role = 'Author'
            order by account_nr) )
, ( Select Rownum r From dual Connect By Rownum <= 300)
where i(+)= r

Answer 2

如果结果超出定义的最小值，则必须将其余部分与并加。

以下是您可以尝试适应情况的方法：

  SELECT i,c FROM  (
select rownum i, c from (
select  'a' c from dual union all select 'b' from dual union all select 'd' from dual union all select 'be' from dual
)), (Select Rownum r From dual Connect By Rownum <= 3)
where (i(+)= r)
union select i,c from (select rownum i, c from (
select  'a' c from dual union all select 'b' from dual union all select 'd' from dual union all select 'be' from dual
)) where i>3

sql占位符行

2 个答案: