使用初始查询合并跨多个数据库的查询？

Question

使用 Data Explorer (SEDE)，我想找出哪些用户在 Stack Overflow 上的声誉超过 200000，以及然后查找他们在其他 Stack Exchange 网站上拥有的任何帐户的详细信息。

这是为列表提供此阈值的查询：

Select id, reputation, accountid
From users
Where reputation > 200000

AccountId 是所有 Stack Exchange 站点的密钥。

我找到了 this query for aggregating across SEDE databases，但是如何根据 previous/baseline 查询的动态结果找到它？

这是我想要的输出类型：

id_so, reputation_so, accounted, other_stackexchange_site_name, reputation_othersite, number_of_answers_other_site, number_of_questions_other_site
1, 250000, 23, serverfault, 500, 5, 1
1, 250000, 23, superuser, 120, 1, 0
2, 300000, 21, serverfault, 300, 3, 2
2, 300000, 21, webmasters, 230, 1, 1
3, 350000, 20, NA, NA, NA, NA
#the case with id 3 has an SO profile with reputation but it has no other profile in other Stack Exchange site

Answer 1

到运行跨数据库的非平凡查询，基于初始查询：

找出所有数据库中的公共键。在这种情况下，它是 AccountId（这是用户的 Stack-Exchange-wide Id）。

创建您的初始查询以将该密钥输入临时文件table。在这种情况下：

CREATE TABLE #UsersOfInterest (AccountId INT)
INSERT INTO  #UsersOfInterest  
    SELECT  u.AccountId
    FROM    Users u
    Where   u.Reputation > 200000

创建另一个 temp table 来保存最终结果（见下文）。

确定查询，在每个站点到运行，获取您想要的信息。例如：

SELECT  u.AccountId, u.DisplayName, u.Reputation, u.Id
        , numQst = (SELECT COUNT(q.Id)  FROM Posts q  WHERE q.OwnerUserId = u.Id  AND q.PostTypeId = 1)
        , numAns = (SELECT COUNT(q.Id)  FROM Posts q  WHERE q.OwnerUserId = u.Id  AND q.PostTypeId = 2)
FROM    Users u
WHERE   u.AccountId = ##seAccntId##

使用系统查询获取适当的数据库。对于 Data Explorer (SEDE)，此类型的查询：

SELECT      name
FROM        sys.databases
WHERE       CASE    WHEN state_desc = 'ONLINE'
                    THEN OBJECT_ID (QUOTENAME (name) + '.[dbo].[PostNotices]', 'U')
            END
            IS NOT NULL

在上述查询上创建游标 并使用它单步执行数据库.
对于每个数据库：
1. 构建一个查询字符串，将第 4 步的查询放入第 3 步的临时 table。
2. 运行查询字符串使用 sp_executesql.
游标完成后，对步骤 3 中的临时 table 执行最终查询。

请参阅 this other answer，了解用于查询所有 Stack Exchange 站点的工作模板。

将它们放在一起，会产生以下查询，您可以运行 live on SEDE:

-- MinMasterSiteRep: User's must have this much rep on whichever site this query is run against
-- MinRep: User's must have this much rep on all other sites

CREATE TABLE #UsersOfInterest (
    AccountId       INT NOT NULL
    , Reputation    INT
    , UserId        INT
    , PRIMARY KEY (AccountId)
)
INSERT INTO  #UsersOfInterest
    SELECT  u.AccountId, u.Reputation, u.Id
    FROM    Users u
    Where   u.Reputation > ##MinMasterSiteRep:INT?200000##

CREATE TABLE #AllSiteResults (
      [Master Rep]          INT
      , [Mstr UsrId]        NVARCHAR(777)
      , AccountId           NVARCHAR(777)
      , [Site name]         NVARCHAR(777)
      , [Username on site]  NVARCHAR(777)
      , [Rep]               INT
      , [# Ans]             INT
      , [# Qst]             INT
)

DECLARE @seDbName       AS NVARCHAR(777)
DECLARE @seSiteURL      AS NVARCHAR(777)
DECLARE @sitePrettyName AS NVARCHAR(777)
DECLARE @seSiteQuery    AS NVARCHAR(max)

DECLARE seSites_crsr CURSOR FOR
WITH dbsAndDomainNames AS (
    SELECT      dbL.dbName
                , STRING_AGG (dbL.domainPieces, '.')    AS siteDomain
    FROM (
        SELECT      TOP 50000   -- Never be that many sites and TOP is needed for order by, below
                    name        AS dbName
                    , value     AS domainPieces
                    , row_number ()  OVER (ORDER BY (SELECT 0)) AS [rowN]
        FROM        sys.databases
        CROSS APPLY STRING_SPLIT (name, '.')
        WHERE       CASE    WHEN state_desc = 'ONLINE'
                            THEN OBJECT_ID (QUOTENAME (name) + '.[dbo].[PostNotices]', 'U') -- Pick a table unique to SE data
                    END
                    IS NOT NULL
        ORDER BY    dbName, [rowN] DESC
    ) AS dbL
    GROUP BY    dbL.dbName
)
SELECT      REPLACE (REPLACE (dadn.dbName, 'StackExchange.', ''), '.', ' ' )  AS [Site Name]
            , dadn.dbName
            , CASE  -- See https://meta.stackexchange.com/q/215071
                    WHEN dadn.dbName = 'StackExchange.Mathoverflow.Meta'
                    THEN 'https://meta.mathoverflow.net/'
                    -- Some AVP/Audio/Video/Sound kerfuffle?
                    WHEN dadn.dbName = 'StackExchange.Audio'
                    THEN 'https://video.stackexchange.com/'
                    -- Ditto
                    WHEN dadn.dbName = 'StackExchange.Audio.Meta'
                    THEN 'https://video.meta.stackexchange.com/'
                    -- Normal site
                    ELSE 'https://' + LOWER (siteDomain) + '.com/'
            END AS siteURL
FROM        dbsAndDomainNames dadn
WHERE       (dadn.dbName = 'StackExchange.Meta'  OR  dadn.dbName NOT LIKE '%Meta%')

-- Step through cursor
OPEN    seSites_crsr
FETCH   NEXT FROM seSites_crsr INTO @sitePrettyName, @seDbName, @seSiteURL
WHILE   @@FETCH_STATUS = 0
BEGIN
    SET @seSiteQuery = '
        USE [' + @seDbName + ']

        INSERT INTO #AllSiteResults
            SELECT
                        uoi.Reputation                                                                                  AS [Master Rep]
                        , ''site://u/'' + CAST(uoi.UserId AS NVARCHAR(88)) + ''|'' + CAST(uoi.UserId AS NVARCHAR(88))   AS [Mstr UsrId]
                        , [AccountId] = ''https://stackexchange.com/users/'' + CAST(u.AccountId AS NVARCHAR(88)) + ''?tab=accounts|'' + CAST(u.AccountId AS NVARCHAR(88))
                        , ''' + @sitePrettyName + '''                                                                   AS [Site name]
                        , ''' + @seSiteURL + ''' + ''u/'' + CAST(u.Id AS NVARCHAR(88)) + ''|'' + u.DisplayName          AS [Username on site]
                        , u.Reputation                                                                                  AS [Rep]
                        , (SELECT COUNT(q.Id)  FROM Posts q  WHERE q.OwnerUserId = u.Id  AND q.PostTypeId = 2)          AS [# Ans]
                        , (SELECT COUNT(q.Id)  FROM Posts q  WHERE q.OwnerUserId = u.Id  AND q.PostTypeId = 1)          AS [# Qst]
            FROM        #UsersOfInterest uoi
            INNER JOIN  Users u                ON uoi.AccountId = u.AccountId
            WHERE       u.Reputation > ##MinRep:INT?200##
    '
    EXEC sp_executesql @seSiteQuery

    FETCH NEXT FROM seSites_crsr INTO @sitePrettyName, @seDbName, @seSiteURL
END
CLOSE       seSites_crsr
DEALLOCATE  seSites_crsr

SELECT      *
FROM        #AllSiteResults
ORDER BY    [Master Rep] DESC, AccountId, [Rep] DESC

它给出的结果如下：

-- 蓝色值超链接的地方。

请注意，用户必须在网站上拥有 200 个代表才能成为 "significant"。这也是该站点包含在 Stack Exchange 风格中所需的代表。

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