Question

我的表格看起来像

    Date    |  BookID   |  Rating  |  Review
2012-10-12  |    2      |    3     |    3
2012-10-13  |    2      |    7     |    9
2012-10-16  |    3      |    4     |    2

每天，一本书都可以获得一些评级和评论我正在尝试编写一个给出两个日期的查询，它显示每本书的评级和评论，在两个给定日期之间的每一天。即使当天没有评级或没有评论，我仍然希望显示日期和BookID 例如，在上表中，我希望查询返回类似

的内容

 Date       |  BookID   |  Rating  |  Review
2012-10-12  |    2      |    3     |    3
2012-10-13  |    2      |    7     |    9
2012-10-14  |    2      |   null   |   null
2012-10-15  |    2      |   null   |   null
2012-10-16  |    3      |    4     |    2

我该怎么办呢？

Answer 1

这样的事情：

<强> SQLFIDDLEEXAMPLE

WITH mycte AS
     (
         SELECT cast('2012-01-01' AS datetime) DateValue
         UNION ALL
         SELECT DateValue + 1
         FROM    mycte
         WHERE   DateValue + 1 < '2014-12-31'
     )


SELECT
CONVERT(char(10), mycte.DateValue,126) as Date,
b.BookID,
(SELECT Rating FROM tbl WHERE BookID = b.BookID
                        AND Date = mycte.DateValue) as Rating,
(SELECT Review FROM tbl WHERE BookID = b.BookID
                        AND Date = mycte.DateValue) as Review
FROM    mycte, (SELECT distinct BookID
               FROM tbl) b
WHERE mycte.DateValue >= '2012-10-12'
AND mycte.DateValue <= '2012-10-15'
OPTION (MAXRECURSION 0)

结果：

|       DATE | BOOKID | RATING | REVIEW |
-----------------------------------------
| 2012-10-12 |      2 |      3 |      3 |
| 2012-10-12 |      3 | (null) | (null) |
| 2012-10-13 |      2 |      7 |      9 |
| 2012-10-13 |      3 | (null) | (null) |
| 2012-10-14 |      2 | (null) | (null) |
| 2012-10-14 |      3 | (null) | (null) |
| 2012-10-15 |      2 | (null) | (null) |
| 2012-10-15 |      3 | (null) | (null) |

Answer 2

--set up test data

DECLARE @Reviews TABLE([Date] date, BookId int, Rating int, Review int)

INSERT INTO @Reviews VALUES
('2012-10-12', 2, 3, 3),
('2012-10-13', 2, 7, 9),
('2012-10-16', 3, 4, 2)

--setup query parameters
DECLARE @StartDate date, 
        @EndDate date
SELECT  @StartDate = '2012-10-12', 
        @EndDate = '2012-10-16'

--run query

;WITH IntervalSet AS
(
    SELECT @StartDate AS [Date]
    UNION ALL
    SELECT DATEADD(DAY,1,[Date]) AS [Date]
    FROM   IntervalSet 
    WHERE  DATEADD(DAY,1,[Date])<=@EndDate
) 
SELECT  I.[Date], B.BookId, R.Rating, R.Review 
FROM    
(
        SELECT  BookId, Min([Date]) as EarliestDate
        FROM    @Reviews
        GROUP BY BookId
) B
JOIN    IntervalSet I
        ON  I.[Date] >= b.EarliestDate
LEFT
JOIN    @Reviews R
        ON  R.[Date] = I.[Date]
        AND R.BookId = B.BookId
ORDER BY I.[Date], B.BookId
OPTION(MAXRECURSION 0)

这给出了结果：

Date       BookId      Rating      Review
---------- ----------- ----------- -----------
2012-10-12 2           3           3
2012-10-13 2           7           9
2012-10-14 2           NULL        NULL
2012-10-15 2           NULL        NULL
2012-10-16 2           NULL        NULL
2012-10-16 3           4           2

这比您发布的结果多了一行，但我认为是正确的 - 在第一次审核之前它没有为bookid返回任何行，这看起来像你之后的那样

SQL查询：将数据链接到两个给定日期之间的所有日期

2 个答案: