stored procedures - How to store SQL result in a variable and parse the result to identify a possible pattern?

Question

The query below

INSERT INTO temp 
SELECT esd, 
       'E' 
FROM   test_data_sovlp 
WHERE  esd IS NOT NULL 
UNION ALL 
SELECT td, 
       CASE is_db 
         WHEN 0 THEN 'S' 
         WHEN 1 THEN 'H' 
       END AS FLAG 
FROM   test_data_sovlp 
WHERE  td IS NOT NULL 

return the following data:

|----------|----------|
|  DT      |  FLAG    |
|----------|----------|
|  10      |  E       |
|  20      |  H       |
|  30      |  E       |
|  40      |  E       |
|  50      |  E       |
|  60      |  S       |
|  70      |  H       |
|  75      |  E       |
|  80      |  H       |
|  100     |  H       |
|----------|----------|

when run against this table:

|----------|----------|----------|----------|----------|
|    ID    |   ESD    |  TD      |   IS_DB  | TEST_SET |
|----------|----------|----------|----------|----------|
|    1     |  10      |  20      |    1     |    2     |
|    2     |  30      |  (null)  |    1     |    2     |
|    3     |  40      |  (null)  |    1     |    2     |
|    4     |  50      |  60      |    0     |    2     |
|    5     |  (null)  |  70      |    1     |    2     |
|    6     |  75      |  100     |    1     |    2     |
|    7     |  (null)  |  80      |    1     |    2     |
|----------|----------|----------|----------|----------|

Note: See the demo here or my previous post here for more details.

What I'm interested in is to concatenate the FLAG value return by the query above, in the DT order.

So for the query above, the concatenation (let's call it q_result) value is: q_result = EHEEESEHH.

I want then to parse then q_result by block of 2 characters to detect the possible presence of any of the following sequence:

HH      EE      HS      SE

During the parse, if a pattern match anywhere in q_result, the proc I would like to write must return 0. If no pattern match then the proc must return 1.

Question

How can this be done ?

Answer 1

If I understand correctly, you can do something like this:

select count(*)
from (select listagg(flag) within group (order by dt) as flags
      from temp
     ) x
where not regexp_like(flags, 'HH|EE|HS|SE');

Alternatively, you can use lag():

select (case when count(*) = sum(case when flag2 not in ('HH', 'EE', 'HS', 'SE')
             then 1 else 0
        end) as return_value
from (select t.*,
             (lag(flag) over (order by dt) || flag) as flag2
      from temp
     ) t;