Sql query: Link data to all days between two given dates - sql

Question

I have a table with that looks like
Date | BookID | Rating | Review
2012-10-12 | 2 | 3 | 3
2012-10-13 | 2 | 7 | 9
2012-10-16 | 3 | 4 | 2
Each day, a book can receive a number of rating and review
I am trying to write a query that given two dates, it displays the rating and review for each book, for EACH day in between the two given dates. Even when that day has no rating or no review I still want to display the date and the BookID
For example, in the table above, I want the query to return something like
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
How can I do this please?

Answer 1

--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)
This gives the results:
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
That's one extra row than the results you posted, but I believe is correct - it doesn't return any rows for a bookid before the first review which looks like what you were after

Answer 2

Something like this:
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)
Result:
| 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) |