sql - 在 sql 记录集中显示相似记录的数量

Question

我有一个表，其中包含 createdate、a、b、c、d、e 字段。我想创建一个显示以下内容的结果集：

createdate,a,b,c,d,e, [在过去 10 分钟内创建的具有相同 b,c,d 的记录数

Answer 1

select  *
,       (
        select  count(*)
        from    YourTable yt2
        where   yt1.b = yt2.b
                and yt1.c = yt2.c
                and yt1.d = yt2.d
                and yt2.createdate between 
                    yt1.createdate - interval 10 minute
                    and yt1.createdate
        ) as DuplicateCount
from    YourTable yt1

yt1.createdate - interval 10 minute语法适用于 MySQL 。对于 SQL Server，使用dateadd(minute, -10, yt1.createdate).

Answer 2

SELECT
    createdate,
    a,
    b,
    c,
    d,
    e,
    duplicatesCount = 
    (
        SELECT count(*) as c
        FROM Table as t2
        WHERE DATEADD(minute, 10, t1.createdate) > GETDATE()
           AND t2.b = t1.b AND t2.c = t1.c AND t2.d = t1.c
    )
    FROM Table as t1