Question

I have a table Lets say “TopicComments” which records each comments from every user on a topic. The table has TopicID and UserID as foreign keys and comment date and comment text. So for each user comment, there will be a record with TopicID, UserID, DateTime, and text.

i want to retrieve the topics with most amount of comments within lets say 5 days. Im not the guy with best SQL skills, so im kind of stuck here. Any help would be appreciated. Not sure if my question makes too much sense.

thanks in advance.

Answer 1

Not mentioning the RDBMS, lets say MS SQL

SELECT  TopicID,
        COUNT(1) TotalCount
FROM    TopicComments
WHERE   CommentDate BETWEEN @StartDate AND @EndDate
GROUP BY TopicID
ORDER BY TotalCount DESC

So a full example would look something like

DECLARE @TopicComments TABLE(
        TopicID INT,
        UserID INT,
        CommentDate DATETIME
)

INSERT INTO @TopicComments SELECT 1, 1, '14 Feb 2010'
INSERT INTO @TopicComments SELECT 1, 1, '14 Feb 2010'
INSERT INTO @TopicComments SELECT 1, 2, '14 Feb 2010'
INSERT INTO @TopicComments SELECT 1, 2, '14 Feb 2010'

INSERT INTO @TopicComments SELECT 2, 1, '14 Feb 2010'
INSERT INTO @TopicComments SELECT 2, 1, '14 Feb 2010'
INSERT INTO @TopicComments SELECT 2, 2, '05 Feb 2010'

DECLARE @StartDate DATETIME,
        @EndDate DATETIME

SELECT  @StartDate = '10 Feb 2010',
        @EndDate = '14 Feb 2010'

SELECT  TopicID,
        COUNT(1) TotalCount
FROM    @TopicComments
WHERE   CommentDate BETWEEN @StartDate AND @EndDate
GROUP BY TopicID
ORDER BY TotalCount DESC

Results

TopicID     TotalCount
----------- -----------
1           4
2           2

To select the TOP 1 would then be

SELECT  TOP 1
        TopicID,
        COUNT(1) TotalCount
FROM    @TopicComments
WHERE   CommentDate BETWEEN @StartDate AND @EndDate
GROUP BY TopicID
ORDER BY TotalCount DESC

EDIT

Use somthing like

DECLARE @StartDate DATETIME,
        @EndDate DATETIME

SET     @EndDate = DATEADD(D, 0, DATEDIFF(D, 0, GETDATE())) --returns only the date part of GETDATE()
SET     @StartDate = @EndDate - 5