问将事件后的多个重复计数为单个重复。

EN

create table #t (Person varchar(10), EventDate date);
insert #t (Person, EventDate)
values
('A', '3/1/14'),
('A', '3/21/14'),
('A', '3/29/14'),
('A', '4/14/14'),
('A', '4/17/14'),
('A', '8/3/14'),
('B', '3/25/14'),
('B', '4/2/14'),
('B', '4/20/14'),
('B', '6/14/14'),
('B', '8/17/14'),
('B', '8/26/14');
;WITH OrderedEvents AS (
    SELECT  Person, EventDate, ROW_NUMBER() OVER (PARTITION BY Person ORDER BY EventDate) AS Ord
    FROM    #t
)
, RepeatedEvents AS (
    SELECT  Person, EventDate, Ord, EventDate AS InitialDate
    FROM    OrderedEvents
    WHERE   Ord = 1
    UNION ALL
    SELECT  o.Person, o.EventDate, o.Ord
            , CASE WHEN DATEDIFF(DAY, r.InitialDate, o.EventDate) > 30 THEN o.EventDate ELSE r.InitialDate END
    FROM    OrderedEvents o
            JOIN RepeatedEvents r ON o.Person = r.Person AND o.Ord = r.Ord + 1
)
, GroupedEvents AS (
    SELECT  Person, MONTH(InitialDate) AS Mth, YEAR(InitialDate) AS Yr
            , IsRepeat = CASE WHEN COUNT(*) > 1 THEN 1 ELSE 0 END
    FROM    RepeatedEvents
    GROUP BY Person, MONTH(InitialDate), YEAR(InitialDate)
)
SELECT  Mth, Yr, CAST(SUM(IsRepeat) AS NUMERIC) / CAST(COUNT(DISTINCT person) AS NUMERIC) AS Pct
FROM    GroupedEvents 
GROUP BY Mth, Yr;