在单个 table 中使用 while 循环的多个 select 查询？可能吗？

Question

我有 2 个 table。 Table A 有日期、ISBN（书籍）、需求（该日期的需求）。 Table B 有日期、ISBN（对于图书）和 SalesRank。

样本数据如下： DailyBookFile 每个日期都有 150k 条记录，从 2010 年开始（即 150k * 365 天 * 8 年）行。 SalesRank Table 也是如此，每个日期有大约 50 万条记录

DailyBookFile       
Date        Isbn13         CurrentModifiedDemandTotal
20180122    9780955153075   13
20180122    9780805863567   9
20180122    9781138779396   1
20180122    9780029001516   9
20180122    9780470614150   42

SalesRank       
importdate  ISBN13          SalesRank
20180122    9780029001516   69499
20180122    9780470614150   52879
20180122    9780805863567   832429
20180122    9780955153075   44528
20180122    9781138779396   926435

Required Output     
Date        Avg_Rank    Book_Group
20180122    385154  Elite
20180121    351545  Elite
20180120    201545  Elite

我想获取每天的Top 200 CurrentModifiedDemand，取平均Rank。

由于我是 SQL 的新手，因此无法找到解决方案。

我从昨天的前 200 个 CurrentModifiedDemand 开始，并获得了去年的平均排名。

SELECT DBF.Filedate AS [Date],
       AVG(AMA.SalesRank) AS Avg_Rank,
       'Elite' AS Book_Group 
FROM [ODS].[wholesale].[DailyBookFile] AS DBF
INNER JOIN [ODS].[MarketplaceMonitor].[SalesRank] AS AMA ON (DBF.Isbn13 = AMA.ISBN13
                                                        AND DBF.FileDate = AMA.importdate)
WHERE DBF.Isbn13 IN (SELECT TOP 200 Isbn13
                     FROM [ODS].[wholesale].[DailyBookFile]
                     WHERE FileDate = 20180122
                       AND CAST(CurrentModifiedDemandTotal AS int) > 200)
  AND DBF.Filedate > 20170101
GROUP BY DBF.Filedate;

但是结果不是我想要的。所以，现在我想要每天前 200 个 CurrentModifiedDemand 的 ISBN 及其平均排名。我试过这个。

DECLARE @i int;
SET @i = 20180122;
WHILE (SELECT DISTINCT(DBF.Filedate)
       FROM [ODS].[wholesale].[DailyBookFile] AS DBF
       WHERE DBF.Filedate = @i) IS NOT NULL
BEGIN

    SELECT DBF.Filedate AS [Date],
           AVG(AMA.SalesRank) AS Avg_Rank,
           'Elite' AS Book_Group 
    FROM [ODS].[wholesale].[DailyBookFile] AS DBF
    INNER JOIN [ODS].[MarketplaceMonitor].[SalesRank] as AMA ON DBF.Isbn13 = AMA.ISBN13
                                                            AND DBF.FileDate = AMA.importdate
    WHERE DBF.Isbn13 in (SELECT TOP 200 Isbn13
                         FROM [ODS].[wholesale].[DailyBookFile]
                         WHERE FileDate = @i
                           AND CAST (CurrentModifiedDemandTotal AS int) > 500)
      AND DBF.Filedate = @i
    GROUP BY DBF.Filedate;

    SET @i = @i+1;

END

在此，我在每个 window 中得到一个 select 查询结果。有什么方法可以在单个 table 中得到结果？

P.S。每天前 200 本书的列表会根据 CurrentModifiedDemand 发生变化。我想拿他们的平均。当天的销售排名。

Answer 1

您可以将行插入临时 table（或 table 类型变量）和 select 所有内容，而不是在循环的每次迭代中立即 selecting循环结束后：

IF OBJECT_ID('tempdb..#books') IS NOT NULL
BEGIN
    DROP TABLE #books
END

CREATE TABLE #books (
    [Date] INT,
    [Avg_Rank] FLOAT,
    [Book_Group] VARCHAR(512)
);

DECLARE @i int;
SET @i = 20180122;

BEGIN TRY
WHILE (SELECT DISTINCT(DBF.Filedate)
    FROM [ODS].[wholesale].[DailyBookFile] AS DBF
    WHERE DBF.Filedate = @i) IS NOT NULL
BEGIN

    INSERT INTO #books (
        [Date],
        [Avg_Rank],
        [Book_Group]
    )
    SELECT DBF.Filedate AS [Date],
        AVG(AMA.SalesRank) AS Avg_Rank,
        'Elite' AS Book_Group 
    FROM [ODS].[wholesale].[DailyBookFile] AS DBF
    INNER JOIN [ODS].[MarketplaceMonitor].[SalesRank] as AMA ON DBF.Isbn13 = AMA.ISBN13
                                                            AND DBF.FileDate = AMA.importdate
    WHERE DBF.Isbn13 in (SELECT TOP 200 Isbn13
                        FROM [ODS].[wholesale].[DailyBookFile]
                        WHERE FileDate = @i
                        AND CAST (CurrentModifiedDemandTotal AS int) > 500)
    AND DBF.Filedate = @i
    GROUP BY DBF.Filedate;

    SET @i = @i+1;

END
END TRY
BEGIN CATCH
    IF OBJECT_ID('tempdb..#books') IS NOT NULL
    BEGIN
        DROP TABLE #books
    END
END CATCH

SELECT *
FROM #books

DROP TABLE #books

使用 table 类型的变量会产生更简单的代码，但是当存储大量数据时 table 类型的变量开始在性能上低于临时 tables。我不确定有多少行是截止的，但根据我的经验，我发现在 10000+ 行计数时将 table 类型的 var 更改为 temp table 会带来显着的性能提升。对于小行数，可能适用相反的情况。

Answer 2

这避免了 昂贵的 WHILE 循环，我相信可以实现您的目标：

CREATE TABLE #DailyBookFile ([Date] date,
                            Isbn13 bigint,
                            CurrentModifiedDemandTotal tinyint);

INSERT INTO #DailyBookFile
VALUES ('20180122',9780955153075,13),
       ('20180122',9780805863567,9 ),
       ('20180122',9781138779396,1 ),
       ('20180122',9780029001516,9 ),
       ('20180122',9780470614150,42);

CREATE TABLE #SalesRank (importdate date,
                        ISBN13 bigint,
                        #SalesRank int);
INSERT INTO #SalesRank
VALUES ('20180122',9780029001516,69499 ),
       ('20180122',9780470614150,52879 ),
       ('20180122',9780805863567,832429),
       ('20180122',9780955153075,44528 ),
       ('20180122',9781138779396,926435);
GO
WITH Ranks AS(
    SELECT SR.*,
           RANK() OVER (PARTITION By SR.importdate ORDER BY SR.#SalesRank) AS Ranking
    FROM #SalesRank SR
         JOIN #DailyBookFile DBF ON SR.ISBN13 = DBF.Isbn13
                               AND SR.importdate = DBF.[Date])
SELECT importdate AS [Date],
       AVG(#SalesRank) AS Avg_rank,
       'Elite' AS Book_Group
FROM Ranks
WHERE Ranking <= 200
GROUP BY importdate;

GO
DROP TABLE #DailyBookFile;
DROP TABLE #SalesRank;

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