Question

当前查询 -

Select Item, Attribute, AttributeValue from table;

Item      Attribute       Attributevalue
1          Color           Brown
1          Width           24
1          Height          36
2          color           white
2          Width           10
2          height          15

我正在尝试将输出设为：

Item     Color    Width    Height
1        brown    24       36
2        white    10       15

Answer 1

这不是字符串聚合，而是旋转。尽管最新版本的Oracle支持pivot关键字，但您也可以使用聚合执行此操作：

select item,
       max(case when attribute = 'Color' then Attributevalue end) as color,
       max(case when attribute = 'Width' then Attributevalue end) as Width,
       max(case when attribute = 'Height' then Attributevalue end) as Height
from table t
group by item;

Answer 2

除了Gordon建议的内容，如果你使用的是11g版本，你可以使用pivot如下

with tab(Item,Attribute,Attributevalue) as
    (select 1,'Color','Brown' from dual union all
     select 1,'Width','24' from dual union all
     select 1,'Height','36' from dual union all
     select 2,'Color','white' from dual union all
     select 2,'Width','10' from dual union all
     select 2,'Height','15' from dual)
------
--end of data preparation
------
select * 
  from tab
 pivot (max(ATTRIBUTEVALUE) for ATTRIBUTE in ('Color' as color,
                                              'Width' as width,
                                              'Height' as height));

输出：

| ITEM | COLOR | WIDTH | HEIGHT |
|------|-------|-------|--------|
|    1 | Brown |    24 |     36 |
|    2 | white |    10 |     15 |

SQL - 如何将多行合并为单个结果集

2 个答案: