如何從表中選擇一組匹配值？

Question

如下表結構：

create table SiteFeatures (
    Feature nvarchar(255), 
    SiteUrl nvarchar(255) 
) 

而下面的示例數據：

Feature  SiteUrl 
Feature1 /sites/a/ 
Feature1 /sites/a/l/ 
Feature2 /sites/a/l/ 
Feature3 /sites/a/l/ 
Feature4 /sites/a/l/rd/ 
Feature5 /sites/a/l/rd/ 
Feature6 /sites/a/l/rd/ 
Feature1 /sites/a/pa/ 
Feature2 /sites/a/pa/ 
Feature3 /sites/a/pa/ 
Feature4 /sites/a/pa/rd/ 
Feature5 /sites/a/pa/rd/ 
Feature6 /sites/a/pa/rd/ 
Feature4 /sites/a/s/rd/ 
Feature5 /sites/a/s/rd/ 
Feature6 /sites/a/s/rd/ 
Feature1 /sites/a/s/ 
Feature2 /sites/a/s/ 
Feature3 /sites/a/s/ 

我想檢索功能的每一個獨特的分組（理想情況下這些功能映射到相應的網站） 。鑑於上面的「分組」示例數據我想返回的結果爲：

Feature1 
Feature1, Feature2, Feature3 
Feature4, Feature5 

如果有相應的站點，那麼：

Feature1 = /sites/a/ 
Feature1,Feature2,Feature3 = /sites/a/l/, /sites/a/pa/, /sites/a/s/ 
Feature4,Feature5,Feature6 = /sites/a/l/rd/, /sites/a/pa/rd/, /sites/a/s/rd/ 

我不是太關心返回結果的格式只只要我有所需的羣體/關係返回。

是否有可能在SQL中做到這一點？

Answer 1

如果你在SQL 2005或更高版本，你可以嘗試：

select distinct 
(
    STUFF 
    (
     (
      SELECT ',' + Feature 
      FROM SiteFeatures t2 
      WHERE t1.SiteUrl = t2.SiteUrl 
      ORDER BY Feature 
      FOR XML PATH(''), TYPE, ROOT 
     ).value('root[1]','nvarchar(max)') 
     ,1,1,'' 
    ) 
) as chars 
from SiteFeatures t1;