sql - Oracle SQL - SELECT CASE WHEN 列=(选择语句)

Question

我想使用 SQL case 表达式选择“up_year”。

如果我这样做就可以了:

SELECT CASE WHEN column1  = '2020' then 'up_year' else 'past_year' else end ;

但是当尝试这样做时:不想每年都改变。

SELECT 
CASE WHEN column1  = (select extract(year from sysdate) from dual) 
then 'up_year' 
else 'past_year' else end ;

Answer 1

您可以使用with例如子句

  with y as (select extract(year from sysdate) year from dual)
  SELECT CASE WHEN column1  = y.year then 'up_year' else 'past_year'  end from y -- and your table

A common table expression (CTE) is a named temporary result set that exists within the scope of a single statement and that can be referred to later within that statement

您可以使用 select into 将其分为两个步骤提取输出的变量然后使用它