SQL - 如何結合Muliple行成一個結果集

Question

當前查詢 -

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 

我試圖得到的輸出是：

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

Answer 1

這不是字符串的聚集，它正在旋轉。雖然最新的Oracle版本支持pivot關鍵字，您可以使用聚合以及做到這一點：

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

除了什麼戈登建議，如果你正在使用11克版本，你可以使用旋轉如下

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)); 

輸出：

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