Question

我有以下数据和一个大问题：在oracle数据库中我有这样的表中的一些数据..

id   version  article 
1      A       B001
2      B       B001 
3      C       B001
4      AA      B001
5      AB      B001
6      Z       B001
7      D       B001

我想从这张表中获得最大版本..

Select MAX(version) from  articles Where article = 'B001'

它给出了＆＃39; Z＆＃39;结果是错误的

但我想＆＃39; AB＆＃39;

Answer 1

with tab(id, version, article) as ( select 1 ,'A', 'B001' from dual union all 
       select 2, 'B', 'B001' from dual union all 
       select 3, 'C', 'B001' from dual union all 
       select 4, 'AA', 'B001' from dual union all 
       select 5, 'AB', 'B001' from dual union all 
       select 6, 'Z', 'B001' from dual union all 
       select 7, 'D', 'B001' from dual)
select  trim(max(lpad(version,3,' '))) ver from tab  where article = 'B001'
group by article;

Answer 2

您可以通过两个步骤来完成，1）比较长度和2）选择它们的最大值：

SELECT MAX(t.version) FROM articles t
WHERE article = 'B0001'
  AND length(t.version) = (SELECT max(length(s.version)) FROM articles s
                           WHERE s.article = 'B0001')

如果您希望所有文章都是动态的：

SELECT t.article, MAX(t.version) FROM articles t
WHERE 
  length(t.version) = (SELECT max(length(s.version)) FROM articles s
                       WHERE s.article = t.article)
GROUP BY t.article

如何从表中最大化Alphabate字符？

2 个答案: