sql - 如何在oracle中为非空值分配等级

Question

我需要以忽略空值的方式分配排名。

select root_cause_desc,
       case 
         when root_cause_desc is null 
         then null  
         else rank() over ( order by excess_value desc) 
       end gap_rank 
 from table.
where root_cause_desc is not null

给予

ROOT_CAUSE_DESC EXCESS_VALUE    TOTAL_EXCESS_VALUE_WK   GAP_RANK

advanced shipment   120.9750138     -760356.4054             10
dfdfdfdf222                0        -1696000.946             11
Root Cause         -0.0760554       -760356.4054             12
test one more      -656.277192      -760356.4054             13
earlier truck      -77099.35         720093.3712             14

它忽略 null 值并为其分配等级，即使对于 null 根本原因也是如此。我希望 gap_rank 为 1,2,3,4。现在请告诉我该怎么做。

Answer 1

问题在于 RANK() 独立于您的 case 语句；它通过您提供的 ORDER BY 子句对整个查询进行排序。

使用 NULLS LAST 关键字将 NULL 值放在订单的末尾，然后您的 CASE 语句将起作用。例如:

with the_data as (
 select level as a
      , nullif(nullif(level, 5), 8) as b
   from dual
 connect by level <= 10
         )
 select a
      , b
      , case when b is null then null
             else rank() over ( order by case when b is not null then 1
                                         end nulls last
                                        , a )
        end as "rank"
   from the_data
  order by a;

         A          B       rank
---------- ---------- ----------
         1          1          1
         2          2          2
         3          3          3
         4          4          4
         5
         6          6          5
         7          7          6
         8
         9          9          7
        10         10          8

10 rows selected.

SQL Fiddle