SQL Server：從查詢返回的動態列

Question

我有一個相對複雜的SQL查詢運行在data.stackexchange.com上。查詢可以在this link找到（並粘貼在下面）。

DECLARE @Location varchar(128) = ##Location:string## 
DECLARE @RepLimit int = ##RepLimit:int## 

SELECT Users.DisplayName, 
     Users.Id, 
     Users.WebsiteUrl, 
     Users.Reputation, 
     (
      SELECT COUNT(*) 
      FROM Posts 
      JOIN PostTags ON Posts.ParentId = PostTags.PostId 
      JOIN Tags ON PostTags.TagId = Tags.Id 
      WHERE Posts.PostTypeId = 2 
      AND Tags.Id = 3 -- Javascript 
      AND Posts.OwnerUserId = Users.Id 
     ) AS JavascriptCount, 

     (
      SELECT COUNT(*) 
      FROM Posts 
      JOIN PostTags ON Posts.ParentId = PostTags.PostId 
      JOIN Tags ON PostTags.TagId = Tags.Id 
      WHERE Posts.PostTypeId = 2 
      AND Tags.Id = 5 -- PHP 
      AND Posts.OwnerUserId = Users.Id 
     ) AS PhpCount, 

     (
      SELECT COUNT(*) 
      FROM Posts 
      JOIN PostTags ON Posts.ParentId = PostTags.PostId 
      JOIN Tags ON PostTags.TagId = Tags.Id 
      WHERE Posts.PostTypeId = 2 
      AND Tags.Id = 820 -- jQuery 
      AND Posts.OwnerUserId = Users.Id 
     ) AS jQueryCount, 

     (
      SELECT COUNT(*) 
      FROM Posts 
      JOIN PostTags ON Posts.ParentId = PostTags.PostId 
      JOIN Tags ON PostTags.TagId = Tags.Id 
      WHERE Posts.PostTypeId = 2 
      AND Tags.Id = 21 -- MySQL 
      AND Posts.OwnerUserId = Users.Id 
     ) AS MySqlCount, 

     (
      SELECT COUNT(*) 
      FROM Posts 
      JOIN PostTags ON Posts.ParentId = PostTags.PostId 
      JOIN Tags ON PostTags.TagId = Tags.Id 
      WHERE Posts.PostTypeId = 2 
      AND Tags.Id = 1386 -- Android 
      AND Posts.OwnerUserId = Users.Id 
     ) AS AndroidCount, 

     (
      SELECT COUNT(*) 
      FROM Posts 
      JOIN PostTags ON Posts.ParentId = PostTags.PostId 
      JOIN Tags ON PostTags.TagId = Tags.Id 
      WHERE Posts.PostTypeId = 2 
      AND Tags.Id IN (58338, 81106, 92809, 7003) -- IOS 
      AND Posts.OwnerUserId = Users.Id 
     ) AS IosCount 

FROM Users 

WHERE Users.Reputation > @RepLimit 
AND Users.Location = @Location 

在上面的查詢，幾件事情：

1. 在data.stackexchange.com，它們生成表單字段，我進入我有DECLARE d頂部的數據（在這種情況下，Location和RepLimit）。
2. 我正在搜索的標籤（Javascript，iOS，Android，PHP等）都是硬編碼的，每個標籤都使用一個子選擇，這並不像我認爲的那樣高效。

我想更改兩件事，但對SQL Server不夠熟悉，不知道它們是否都可行（也不知道查詢結果是什麼）。這兩個變化是：

1. 我想優化查詢。現在，我覺得做出六個幾乎相同的子選擇不是實現最終結果的理想方式。
2. 我希望標籤列表作爲新表單元素中的逗號分隔列表（如頂部的DECLARE d，比如Location和RepLimit）或5個單獨的表單域（限制查詢到多達5個不同的標籤）

有沒有人有類似的查詢（或類似的問題，有實際的列返回查詢是動態的？任何幫助表示讚賞。

Answer 1

至於這裏的第一個問題是優化查詢方式：

DECLARE @Location varchar(128) = ##Location:string## 
DECLARE @RepLimit int = ##RepLimit:int## 

SELECT Users.DisplayName, 
     Users.Id, 
     Users.WebsiteUrl, 
     Users.Reputation, 
     sum(case when Tags.Id = 3 then 1 else 0 end) as JavascriptCount, 
     sum(case when Tags.Id = 5 then 1 else 0 end) as PhpCount, 
     sum(case when Tags.Id = 820 then 1 else 0 end) as jQueryCount, 
     sum(case when Tags.Id = 21 then 1 else 0 end) as MySqlCount, 
     sum(case when Tags.Id = 1386 then 1 else 0 end) as AndroidCount, 
     sum(case when Tags.Id IN (58338, 81106, 92809, 7003) then 1 else 0 end) as IosCount 

FROM Users 
    JOIN Posts ON Posts.OwnerUserId = Users.Id 
     JOIN PostTags ON Posts.ParentId = PostTags.PostId 
      JOIN Tags ON PostTags.TagId = Tags.Id 

WHERE Users.Reputation > @RepLimit AND Posts.PostTypeId = 2 
AND Users.Location = @Location 

GROUP BY 
     Users.DisplayName, 
     Users.Id, 
     Users.WebsiteUrl, 
     Users.Reputation 

至於你的第二個問題，我 - 作爲一無所知那些stackexchange形式 - 恐怕我也沒有辦法。但既然你提到逗號分隔列表，你可以利用SQL的CHARINDEX（）函數來查找參數中的Tags.Id。這樣的：

case when CHARINDEX(','+convert(varchar,Tags.Id)+',',','+@List1+',') <> 0 then 1 else 0 end