Sql server 如何识别表中的哪些行满足特定条件，但该条件基于前几行中的数据？提供的例子
我正在使用一个包含以下数据的表：Sql server 如何识别表中的哪些行满足特定条件，但该条件基于前几行中的数据？提供的例子,sql-server,tsql,Sql Server,Tsql,我正在使用一个包含以下数据的表： ObjectId EventId EventDate 1 342 2017-10-27 1 342 2018-01-06 1 343 2018-04-18 1 401 2018-10-15 1 342 2018-11-12 1 342 2018-11-29 1
ObjectId EventId EventDate
1 342 2017-10-27
1 342 2018-01-06
1 343 2018-04-18
1 401 2018-10-15
1 342 2018-11-12
1 342 2018-11-29
1 401 2018-12-10
1 342 2019-02-21
1 343 2019-04-23
1 401 2019-11-04
1 343 2020-02-15
2 342 2018-06-08
2 343 2018-09-18
2 342 2018-10-02
ObjectId EventId EventDate EventsComplete
1 342 2017-10-27 0
1 342 2018-01-06 0
1 343 2018-04-18 0
1 401 2018-10-15 1
1 342 2018-11-12 0
1 342 2018-11-29 0
1 401 2018-12-10 0
1 342 2019-02-21 0
1 343 2019-04-23 1
1 401 2019-11-04 0
1 343 2020-02-15 0
2 342 2018-06-08 0
2 343 2018-09-18 0
2 342 2018-10-02 0
select 1 as ObjectId, 342 as EventId, cast('2017-10-27' as date) as EventDate
union select 1 as ObjectId, 342 as EventId, cast('2018-01-06' as date) as EventDate
union select 1 as ObjectId, 343 as EventId, cast('2018-04-18' as date) as EventDate
union select 1 as ObjectId, 401 as EventId, cast('2018-10-15' as date) as EventDate
union select 1 as ObjectId, 342 as EventId, cast('2018-11-12' as date) as EventDate
union select 1 as ObjectId, 342 as EventId, cast('2018-11-29' as date) as EventDate
union select 1 as ObjectId, 401 as EventId, cast('2018-12-10' as date) as EventDate
union select 1 as ObjectId, 342 as EventId, cast('2019-02-21' as date) as EventDate
union select 1 as ObjectId, 343 as EventId, cast('2019-04-23' as date) as EventDate
union select 1 as ObjectId, 401 as EventId, cast('2019-11-04' as date) as EventDate
union select 1 as ObjectId, 343 as EventId, cast('2020-02-15' as date) as EventDate
union select 2 as ObjectId, 342 as EventId, cast('2018-06-08' as date) as EventDate
union select 2 as ObjectId, 343 as EventId, cast('2018-09-18' as date) as EventDate
union select 2 as ObjectId, 342 as EventId, cast('2018-10-02' as date) as EventDate
也许有一种方法可以通过CTE或直接SQL来实现这一点，但我无法使用这两种方法中的任何一种找到有效的解决方案 我能想到的最好的解决方案是通过RBAR（一行接一行）使用要处理的数据的非游标结果集。这是我了解如何管理当前ObjectId的事件状态的唯一方法 您可以在SSMS中运行以下操作：
-- Declare a temporary table for housing the queried data.
DECLARE @Data TABLE ( ObjectId INT, EventId INT, EventDate DATE, EventsComplete BIT DEFAULT (0), pk INT IDENTITY(1,1) );
-- Fetch the queried data into a table variable for processing.
INSERT INTO @Data ( ObjectId, EventId, EventDate ) VALUES
( 1, 342, '2017-10-27' ),( 1, 342, '2018-01-06' ),( 1, 343, '2018-04-18' ),( 1, 401, '2018-10-15' ),( 1, 342, '2018-11-12' ),
( 1, 342, '2018-11-29' ),( 1, 401, '2018-12-10' ),( 1, 342, '2019-02-21' ),( 1, 343, '2019-04-23' ),( 1, 401, '2019-11-04' ),
( 1, 343, '2020-02-15' ),( 2, 342, '2018-06-08' ),( 2, 343, '2018-09-18' ),( 2, 342, '2018-10-02' );
/*
I'm inserting the sample data you provided, however, in your code you would simply SELECT/INSERT
the required data into the temporary table @Data while sorting on your ObjectId and EventDate.
*/
-- Declare some variables for processing.
DECLARE
@ObjectId INT,
@EventId INT,
@PrevObjId INT,
@Flag342 BIT,
@Flag343 BIT,
@Flag401 BIT;
-- For-each row in @Data (non-cursor)...
DECLARE @pk INT = 1;
WHILE @pk <= ( SELECT MAX ( pk ) FROM @Data ) BEGIN
-- Current row.
SELECT
@ObjectId = ObjectId,
@PrevObjId = ISNULL ( @PrevObjId, ObjectId ),
@EventId = EventId
FROM @Data WHERE pk = @pk;
-- Set the event flags.
IF @EventId = 342
SET @Flag342 = 1;
IF @EventID = 343
SET @Flag343 = 1;
IF @EventId = 401
SET @Flag401 = 1;
IF @ObjectId = @PrevObjId BEGIN
-- Check for a completed event.
IF ( @Flag342 = 1 AND @Flag343 = 1 AND @Flag401 = 1 ) BEGIN
-- Set the EventsComplete flag.
UPDATE @Data SET EventsComplete = 1 WHERE pk = @pk;
-- Reset the event flag values.
SELECT @Flag342 = 0, @Flag343 = 0, @Flag401 = 0;
END
END ELSE BEGIN
-- New ObjectId, reset the event flag values.
SELECT
@Flag342 = CASE WHEN @EventId = 342 THEN 1 ELSE 0 END,
@Flag343 = CASE WHEN @EventId = 343 THEN 1 ELSE 0 END,
@Flag401 = CASE WHEN @EventId = 401 THEN 1 ELSE 0 END;
END
-- Next row.
SELECT
@PrevObjId = @ObjectId,
@pk = ( @pk + 1 );
END
-- Return the updated resultset.
SELECT
ObjectId, EventId, EventDate, EventsComplete
FROM @Data ORDER BY pk;
下面是基于集合的解决方案 除使用位字段外，未尝试任何优化过程。它起作用了，我受够了。我可以看到一些可能的简化点 我应该补充一点，事实上，这个问题目前还没有定义，因为如果两个不同的事件可以在同一天发生，那么我们对它们发生的顺序没有定义。因此，在这些情况下，在第一个CTE中分配的行号是任意的。样本数据中未出现此类情况 使用字符串连接路径-150毫秒 切换到位而不是字符串，仍然比光标慢（~30ms）
下面的代码演示了使用CTE解决问题的另一种方法。第一阶段添加一列（
RNE342DoneObjectId-- Sample data.
declare @ObjectEvents as Table ( ObjectId Int, EventId Int, EventDate Date );
insert into @ObjectEvents ( ObjectId, EventId, EventDate ) values
( 1, 342, '2017-10-27' ),( 1, 342, '2018-01-06' ),( 1, 343, '2018-04-18' ),( 1, 401, '2018-10-15' ),( 1, 342, '2018-11-12' ),
( 1, 342, '2018-11-29' ),( 1, 401, '2018-12-10' ),( 1, 342, '2019-02-21' ),( 1, 343, '2019-04-23' ),( 1, 401, '2019-11-04' ),
( 1, 343, '2020-02-15' ),( 2, 342, '2018-06-08' ),( 2, 343, '2018-09-18' ),( 2, 342, '2018-10-02' );
select * from @ObjectEvents order by ObjectId, EventDate;
-- Do the deed.
with
OrderedEventsByObject as (
-- Number the rows for each ObjectId in EventDate order and add flags for the events.
select ObjectId, EventId, EventDate,
Row_Number() over ( partition by ObjectId order by EventDate ) as RN,
case when EventId = 342 then 1 else 0 end as E342Done,
case when EventId = 343 then 1 else 0 end as E343Done,
case when EventId = 401 then 1 else 0 end as E401Done
from @ObjectEvents ),
ProcessedEvents as (
-- Process the events in order for each ObjectId .
-- Start with the first row for the ObjectId ...
select ObjectId, EventId, EventDate, RN, E342Done, E343Done, E401Done,
0 as EventsComplete
from OrderedEventsByObject
where RN = 1
union all
-- ... then add the next row, if any, for each ObjectId :
select OEBO.ObjectId, OEBO.EventId, OEBO.EventDate, OEBO.RN,
-- Use arithmetic as a shorthand for: ( PE.E342Done or OEBO.E342Done ) and not PH.EventsComplete .
Sign( ( PE.E342Done + OEBO.E342Done ) * ( 1 - PH.EventsComplete ) ),
Sign( ( PE.E343Done + OEBO.E343Done ) * ( 1 - PH.EventsComplete ) ),
Sign( ( PE.E401Done + OEBO.E401Done ) * ( 1 - PH.EventsComplete ) ),
PH.EventsComplete
from ProcessedEvents as PE inner join
OrderedEventsByObject as OEBO on OEBO.ObjectId = PE.ObjectId and OEBO.RN = PE.RN + 1 cross apply
-- Use cross apply to make the EventsCompleted column available within the recursive part of the CTE.
-- Arithmetic is used again to check for one of every event type being completed.
( select case when Sign( PE.E342Done + OEBO.E342Done ) + Sign( PE.E343Done + OEBO.E343Done ) + Sign( PE.E401Done + OEBO.E401Done ) = 3 then 1 else 0 end as EventsComplete ) as PH
)
-- You can uncomment the following select statements to see the intermediate results:
-- select * from OrderedEventsByObject;
-- select * from ProcessedEvents;
select ObjectId, EventId, EventDate, EventsComplete
from ProcessedEvents
order by ObjectId, RN;
事件是否必须按特定顺序发生？一个日期可以发生多个事件吗？@HABO事件可以以任何顺序发生。一个日期可以发生多个事件。同一事件可能会在同一个日期发生两次。我自己还没有玩过这一次，但我已经将它添加到书签，让它试一试。然而，我看到它的第一反应是“这可能是使用光标的好时机”。这两个原因都是因为逻辑变得非常简单，而且我敢打赌，由于性能接近于使用行号和多根递归之类的神秘的基于集合的解决方案，乍一看，在递归CTE中使用相同的逻辑应该是简单的，如果有点笨拙的话，递归已经失控了，特别是考虑到不知道它能深入多少层。这就是为什么我选择这种方法来保持它的简单性——更不用说可维护性了。递归元素只需要两个级别，因为它可以使用类似
where next.eventid！=this.eventid或last.eventid和next.row number>this.row number和next.objectid=this.objectid和p.bits&n.bits=0candidates符号（（PE.E342Done+OEBO.E342Done）*（1-PH.EventsComplete））select 1 as ObjectId, 342 as EventId, cast('2017-10-27' as date) as EventDate
into t
union all select 1, 342, cast('2018-01-06' as date)
union all select 1, 343, cast('2018-04-18' as date)
union all select 1, 401, cast('2018-10-15' as date)
union all select 1, 342, cast('2018-11-12' as date)
union all select 1, 342, cast('2018-11-29' as date)
union all select 1, 401, cast('2018-12-10' as date)
union all select 1, 342, cast('2019-02-21' as date)
union all select 1, 343, cast('2019-04-23' as date)
union all select 1, 401, cast('2019-11-04' as date)
union all select 1, 343, cast('2020-02-15' as date)
union all select 2, 342, cast('2018-06-08' as date)
union all select 2, 343, cast('2018-09-18' as date)
union all select 2, 342, cast('2018-10-02' as date);
go
with numbered as
-- just adding a row number to make it easier to follow
(
select objectid,
eventid,
eventdate,
rn = row_number() over (partition by objectid order by eventdate asc),
bits = cast(power(2, case eventid when 342 then 0 when 343 then 1 else 2 end) as tinyint)
from t
),
paths as
-- the concatenated paths of distinct eventid for each row, as a bitfield
(
select n.objectid,
n.eventid,
n.eventdate,
root = n.rn,
n.rn,
bits
from numbered n
union all
select n.objectid,
n.eventid,
n.eventdate,
p.root,
n.rn,
p.bits | n.bits
from paths p
join numbered n on n.objectid = p.objectid
and n.rn > p.rn
and p.bits & n.bits = 0
),
candidates as
-- a row that has a path containing all 3 values (bits = 7)
(
select *
from (
select root,
rn,
candidate = iif
(
rn = min(rn) over (partition by root),
1, 0
)
from paths
where bits = 7
) c
where c.candidate = 1
)
-- get the candidate rows where no earlier candidiate in row number order
-- has a root-to-end path which overlaps the path for this candidate
select distinct
n.objectid,
n.eventid,
n.eventdate,
isnull(c.candidate, 0)
from numbered n
left join candidates c on c.rn = n.rn
and not exists
(
select *
from candidates prev
where prev.rn < c.rn
and prev.rn > c.root
and prev.root < c.rn
)
order by n.objectid,
n.eventdate,
n.eventid
declare @triplets table(objectid int, eventid int, eventdate date);
declare c cursor fast_forward for
select objectid, eventid, eventdate from t order by objectid, eventdate asc;
declare
@ob int, @prevob int, @event int, @dt date,
@bits tinyint = 0;
open c;
fetch next from c into @ob, @event, @dt;
while @@fetch_status = 0
begin
if (@ob = @prevob)
begin
if @event = 342 set @bits |= 1;
else if @event = 343 set @bits |= 2;
else if @event = 401 set @bits |= 4;
if (@bits = 7)
begin
insert @triplets values (@ob, @event, @dt);
set @bits = 0
end
end
else select @bits = 0, @prevob = @ob;
fetch next from c into @ob, @event, @dt;
end
close c;
deallocate c;
select t.*, iif(tt.objectid is null, 0, 1)
from t
left join @triplets tt on t.objectid = tt.objectid
and t.eventid = tt.eventid
and t.eventdate = tt.eventdate;
-- Sample data.
declare @ObjectEvents as Table ( ObjectId Int, EventId Int, EventDate Date );
insert into @ObjectEvents ( ObjectId, EventId, EventDate ) values
( 1, 342, '2017-10-27' ),( 1, 342, '2018-01-06' ),( 1, 343, '2018-04-18' ),( 1, 401, '2018-10-15' ),( 1, 342, '2018-11-12' ),
( 1, 342, '2018-11-29' ),( 1, 401, '2018-12-10' ),( 1, 342, '2019-02-21' ),( 1, 343, '2019-04-23' ),( 1, 401, '2019-11-04' ),
( 1, 343, '2020-02-15' ),( 2, 342, '2018-06-08' ),( 2, 343, '2018-09-18' ),( 2, 342, '2018-10-02' );
select * from @ObjectEvents order by ObjectId, EventDate;
-- Do the deed.
with
OrderedEventsByObject as (
-- Number the rows for each ObjectId in EventDate order and add flags for the events.
select ObjectId, EventId, EventDate,
Row_Number() over ( partition by ObjectId order by EventDate ) as RN,
case when EventId = 342 then 1 else 0 end as E342Done,
case when EventId = 343 then 1 else 0 end as E343Done,
case when EventId = 401 then 1 else 0 end as E401Done
from @ObjectEvents ),
ProcessedEvents as (
-- Process the events in order for each ObjectId .
-- Start with the first row for the ObjectId ...
select ObjectId, EventId, EventDate, RN, E342Done, E343Done, E401Done,
0 as EventsComplete
from OrderedEventsByObject
where RN = 1
union all
-- ... then add the next row, if any, for each ObjectId :
select OEBO.ObjectId, OEBO.EventId, OEBO.EventDate, OEBO.RN,
-- Use arithmetic as a shorthand for: ( PE.E342Done or OEBO.E342Done ) and not PH.EventsComplete .
Sign( ( PE.E342Done + OEBO.E342Done ) * ( 1 - PH.EventsComplete ) ),
Sign( ( PE.E343Done + OEBO.E343Done ) * ( 1 - PH.EventsComplete ) ),
Sign( ( PE.E401Done + OEBO.E401Done ) * ( 1 - PH.EventsComplete ) ),
PH.EventsComplete
from ProcessedEvents as PE inner join
OrderedEventsByObject as OEBO on OEBO.ObjectId = PE.ObjectId and OEBO.RN = PE.RN + 1 cross apply
-- Use cross apply to make the EventsCompleted column available within the recursive part of the CTE.
-- Arithmetic is used again to check for one of every event type being completed.
( select case when Sign( PE.E342Done + OEBO.E342Done ) + Sign( PE.E343Done + OEBO.E343Done ) + Sign( PE.E401Done + OEBO.E401Done ) = 3 then 1 else 0 end as EventsComplete ) as PH
)
-- You can uncomment the following select statements to see the intermediate results:
-- select * from OrderedEventsByObject;
-- select * from ProcessedEvents;
select ObjectId, EventId, EventDate, EventsComplete
from ProcessedEvents
order by ObjectId, RN;