Find a row that has passed different steps in the same table - sql

Question

Hi to all here it is my problem:
I have an history table where a record register different steps:
Id
Step
Item Code
1
Created
112345
2
Approved
112345
3
Completed
112345
4
Closed
112345
5
Created
112346
6
Approved
112346
8
Closed
112346
What i want to find inside this table is:
All the item codes that have done one step (for example the Approved one) and where the next one is not the "natural one" (for expample the Completed one). In the example table the time code 112346 item has done the Approved step but has skipped the Completed step).
Is there anyway to do a query like this? I've used the PARTITION BY to make a cluster of Item ,for each step, but i am unable to continue the query.
Thanks in advance for any help or suggestion

Answer 1

You can use the LEAD analytic function to check if the next step is not the expected one:
SELECT id, step, item_code
FROM (
SELECT t.*,
LEAD(step) OVER (PARTITION BY item_code ORDER BY id) AS next_step
FROM table_name t
)
WHERE step = 'Approved'
AND (next_step IS NULL OR next_step != 'Completed')
Or, from Oracle 12, you can use MATCH_RECOGNIZE to perform row-by-row processing:
SELECT id, step, item_code
FROM table_name
MATCH_RECOGNIZE(
PARTITION BY item_code
ORDER BY id
ALL ROWS PER MATCH
PATTERN ( approved {- (not_completed|$) -} )
DEFINE
approved AS step = 'Approved',
not_completed AS step <> 'Completed'
)
Which, for the sample data:
CREATE TABLE table_name (Id, Step, Item_Code) AS
SELECT 1, 'Created', 112345 FROM DUAL UNION ALL
SELECT 2, 'Approved', 112345 FROM DUAL UNION ALL
SELECT 3, 'Completed', 112345 FROM DUAL UNION ALL
SELECT 4, 'Closed', 112345 FROM DUAL UNION ALL
SELECT 5, 'Created', 112346 FROM DUAL UNION ALL
SELECT 6, 'Approved', 112346 FROM DUAL UNION ALL
SELECT 8, 'Closed', 112346 FROM DUAL;
Both output:
ID
STEP
ITEM_CODE
6
Approved
112346
db<>fiddle here

Answer 2

Provided you have a table of step names with a proper ordering int column (seqno)
with
/* Sample data */
steps(seqno, Step) as (
select 1, 'Created' from dual union all
select 2, 'Approved' from dual union all
select 3, 'Completed' from dual union all
select 4, 'Closed' from dual
),
tbl(Id, Step, ItemCode) as (
select 1, 'Created' , 112345 from dual union all
select 2, 'Approved' , 112345 from dual union all
select 3, 'Completed', 112345 from dual union all
select 4, 'Closed' , 112345 from dual union all
select 5, 'Created' , 112346 from dual union all
select 6, 'Approved' , 112346 from dual union all
select 8, 'Closed' , 112346 from dual
),
/* Find steps with the next step being out of order */
m as (
select max(seqno)+1 term
from steps
)
select Id, Step, ItemCode
from (
SELECT t.*, s.seqno, lead(s.seqno, 1, (select term from m)) over(partition by ItemCode order by Id) nextSeqno
FROM tbl t
JOIN steps s on s.Step = t.Step
) q
cross join m
where nextseqno != Seqno + 1 and nextseqno < m.term