Using SQL to find a match in consecutive data

Question

Hi
I am trying to find a way (within a single SQL statement if possible) that will return a value based on whether a match is found between two points of data.
Please let me demonstrate:
create table
routetest
as
select
1 routeid,
0000 routeposition,
null actiontype,
null activityid
from dual
UNION
select
1 ,1000, 'Delay', null
from dual
UNION
select
1 ,1100, 'Activity', 'Letter'
from dual
UNION
select
1 ,1200, 'Activity', 'SMS'
from dual
UNION
select
1 ,1300, 'Activity', 'Email'
from dual
UNION
select
1 ,1400, 'Activity', 'Bar'
from dual
UNION
select
1 ,1500, 'Delay', null
from dual
UNION
select
1 ,1600, 'Activity', 'SMS'
from dual
UNION
select
1 ,1700, 'Delay', null
from dual
UNION
select
1 ,1800, 'Activity', 'Letter'
from dual
UNION
select
1 ,1900, 'Activity', 'SMS'
from dual
UNION
select
1 ,2000, null, null
from dual;
select * from routetest order by 1,2
ROUTEID ROUTEPOSITION ACTIONTYPE ACTIVITYID
      1             0                     
      1          1000 Delay               
      1          1100 Activity   Letter   
      1          1200 Activity   SMS      
      1          1300 Activity   Email    
      1          1400 Activity   Bar      
      1          1500 Delay               
      1          1600 Activity   SMS      
      1          1700 Delay               
      1          1800 Activity   Letter   
      1          1900 Activity   SMS      
      1          2000                     
12 rows selectedReturn a value where, for startpos X does activity Y exist between X and last activity before non-activity/end.
Return
0 for no - it does not,
1 for yes, at the current position and
2 for yes, after the current position (but before before the next non-activity)
Expected results:
Startpos=0
Activity=Letter
Returns: 0
Startpos=1000
Activity=Letter
Returns: 2
Startpos=1100
Activity=Letter
Returns: 1
Startpos=1000
Activity=Bar
Returns: 2
Startpos=1100
Activity=Bar
Returns: 2
Startpos=1400
Activity=Bar
Returns: 1
Startpos=1400
Activity=Bar
Returns: 1
Startpos=1500
Activity=Letter
Returns: 0
Startpos=1600
Activity=Letter
Returns: 0
Startpos=1700
Activity=Letter
Returns: 2
Does that make any sense?
Thanks
Martin

Answer 1

Hi, Martin,
Thanks for posting the sample data so clearly. Could you post the results you want from that data just as clearly?
I'm fairly sure you want to compute something like grp_num in the query below, so you can tell that (for example) routepostition 1000 is in the same group as 1100, but not 1600.
I'm less sure what you want beyoned that. Also, I'm just guessing at what role routeid plays in this problem.
WITH     got_grp_num     AS
     SELECT     routetest.*
     ,     ROW_NUMBER ()      OVER ( PARTITION BY  routeid
                              ORDER BY     routeposition
           - COUNT (activityid) OVER ( PARTITION BY  routeid
                              ORDER BY     routeposition
                            )     AS grp_num
     FROM     routetest
SELECT       routeid, routeposition, actiontype, activityid
,       CASE
          WHEN  activityid   IS NULL     THEN  0
          WHEN  activityid   = 'Letter'     THEN  1
          WHEN  1 <= SUM ( CASE
                         WHEN  activityid = 'Letter'
                         THEN  1
                         END
                      ) OVER ( PARTITION BY  routeid
                            ,           grp_num
                             )          THEN 2
                              ELSE 0
       END     AS letter_code
FROM       got_grp_num
ORDER BY  routeid, routeposition
;The query above produces these results:
   ROUTEID ROUTEPOSITION ACTIONTY ACTIVI LETTER_CODE
         1             0                           0
         1          1000 Delay                     0
         1          1100 Activity Letter           1
         1          1200 Activity SMS              2
         1          1300 Activity Email            2
         1          1400 Activity Bar              2
         1          1500 Delay                     0
         1          1600 Activity SMS              0
         1          1700 Delay                     0
         1          1800 Activity Letter           1
         1          1900 Activity SMS              2
         1          2000                           0I know that's not exactly what you want, but I hope it gives you some ideas.