Group by values that are in sequence - sql

Question

I have some table like this
row chequeNo
1 15
2 19
3 20
4 35
5 16
and I need to get the result like this
row from to
1 15 16
2 19 20
3 35 35
so I need groups of chequeNo where values would be sequential without any interruptions. chequeNo is unique column. Additionally it should be done with one sql select query, because I haven't permissions to create any sql structures except select queries.
So is it possible?
Would be grateful for any help

Answer 1

You can use Aketi Jyuuzou's technique called Tabibitosan here:
SQL> create table mytable (id,chequeno)
2 as
3 select 1, 15 from dual union all
4 select 2, 19 from dual union all
5 select 3, 20 from dual union all
6 select 4, 35 from dual union all
7 select 5, 16 from dual
8 /
Table created.
SQL> with tabibitosan as
2 ( select chequeno
3 , chequeno - row_number() over (order by chequeno) grp
4 from mytable
5 )
6 select row_number() over (order by grp) "row"
7 , min(chequeno) "from"
8 , max(chequeno) "to"
9 from tabibitosan
10 group by grp
11 /
row from to
---------- ---------- ----------
1 15 16
2 19 20
3 35 35
3 rows selected.
Regards,
Rob.

Answer 2

This should work with Oracle 10 (only tested with Oracle 11)
select group_nr + 1,
min(chequeno) as start_value,
max(chequeno) as end_value
from (
select chequeno,
sum(group_change_flag) over (order by rn) as group_nr
from (
select row_number() over (order by chequeno) as rn,
chequeno,
case
when chequeno - lag(chequeno,1,chequeno) over (order by chequeno) <= 1 then 0
else 1
end as group_change_flag
from foo
) t1
) t2
group by group_nr
order by group_nr
(it should work with any DBMS supporting standard SQL windowing functions, e.g. PostgreSQL, DB2, SQL Server 2012)

Answer 3

Here is a "plain vanilla" approach:
SELECT T1.chequeNo, T2.chequeNo
FROM Table1 AS T1 INNER JOIN Table1 AS T2 ON T2.chequeNo >= T1.chequeNo
WHERE
NOT EXISTS (SELECT T0.chequeNo FROM Table1 T0 WHERE T0.chequeNo IN ((T1.chequeNo-1), (T2.chequeNo+1)))
AND (SELECT COUNT(*) FROM Table1 T0 WHERE T0.chequeNo BETWEEN T1.chequeNo AND T2.chequeNo)=(T2.chequeNo - T1.chequeNo + 1)
ORDER BY 1,2
Please let me know if it's too inefficient for large data sets.

Answer 4

CREATE TABLE YOUR_TABLE (
chequeNo NUMBER PRIMARY KEY
);
INSERT INTO YOUR_TABLE VALUES (15);
INSERT INTO YOUR_TABLE VALUES (19);
INSERT INTO YOUR_TABLE VALUES (20);
INSERT INTO YOUR_TABLE VALUES (35);
INSERT INTO YOUR_TABLE VALUES (16);
SELECT T1.chequeNo "from", T2.chequeNo "to"
FROM
(
SELECT chequeNo, ROW_NUMBER() OVER (ORDER BY chequeNo) RN
FROM (
SELECT chequeNo, LAG(chequeNo) OVER (ORDER BY chequeNo) PREV
FROM YOUR_TABLE
)
WHERE PREV IS NULL OR chequeNo > PREV + 1
) T1
JOIN
(
SELECT chequeNo, ROW_NUMBER() OVER (ORDER BY chequeNo) RN
FROM (
SELECT chequeNo, LEAD(chequeNo) OVER (ORDER BY chequeNo) NEXT
FROM YOUR_TABLE
)
WHERE NEXT IS NULL OR chequeNo < NEXT - 1
) T2
USING (RN);
Result:
from to
---------------------- ----------------------
15 16
19 20
35 35
If we spice things up a little...
INSERT INTO YOUR_TABLE VALUES (17);
INSERT INTO YOUR_TABLE VALUES (18);
...we get:
from to
---------------------- ----------------------
15 20
35 35