Question

我有一张表让我们说“TopicComments”，它记录每个用户对主题的每条评论。该表具有TopicID和UserID作为外键和注释日期和注释文本。因此，对于每个用户评论，都会有一个包含TopicID，UserID，DateTime和文本的记录。

我希望在5天内检索具有大量评论的主题。我不是那种具有最佳SQL技能的人，所以我有点卡在这里。任何帮助，将不胜感激。不确定我的问题是否有太多意义。

提前感谢。

Answer 1

不提RDBMS，比方说MS SQL

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

所以完整示例看起来像

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

结果

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

选择 TOP 1 将是

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

修改

使用像
这样的东西
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

Answer 2

您应该在sql语句中使用 GROUP BY 按TopicID对所有注释进行分组，而不是sum（）

像那样^

选择TopicID，sum（UserID）来自 TopicComments WHERE DateTime＆gt; 日期 5天抵消 GROUP BY TopicID ORDER BY sum（UserID）;

根据某些条件从表中获取热门条目

2 个答案: