Sql query for start and end of a column - sql

Question

I am trying to write a query to get start and end serials for a particular sale
Serial Sale_id
0001 1
0002 1
0003 1
0004 2
0005 2
0006 1
0007 1
0008 1
I am looking for a result like
Quantity Start End
3 0001 0003
3 0006 0008
can some one please help me get this one right

Answer 1

This query (adapted from the book SQL MVP Deep Dives) should give you what you want:
SELECT
Sale_id, --optional, include is you want the Sale_id
-- if Serial is a (VAR)CHAR type use this field
Quantity = MAX(CAST(Serial AS INT)) - MIN(CAST(Serial AS INT)) + 1,
-- if Serial is INT already use this field instead
--Quantity = MAX(CAST(Serial AS INT)) - MIN(CAST(Serial AS INT)) + 1,
[Start] = MIN(Serial),
[End] = MAX(Serial)
FROM (
SELECT
Sale_id,
Serial,
RowNumber =
Serial - ROW_NUMBER() OVER (PARTITION BY Sale_id ORDER BY Serial)
FROM YourTable
) a
--WHERE Sale_id = 1 -- optional limiting WHERE clause
--WHERE Sale_id IN (1,2) -- optional limiting WHERE clause
GROUP BY Sale_id, RowNumber
ORDER BY Start;
I made the assumption that Serial is stored as a character type and included a cast to INT. If it is an numeric type already, change to the line without the cast for the Quantity.
I choose to include the Sale_id column in the output, if you don't want it, just comment it out. If you want to limit the results to one or more particular Sale_id include one of the the WHERE clauses.
Sample SQL Fiddle
Sample output:
Sale_id Quantity Start End
----------- ----------- ---------- ----------
1 3 0001 0003
2 2 0004 0005
1 3 0006 0008
(3 row(s) affected)

Answer 2

You can do this by counting the number of non-similar sales ids before each one. This is a constant for sequences where the sales ids are the same. Then use this for grouping:
select count(*), min(serial_no), max(serial_no)
from (select t.*,
(select count(*)
from taple t2
where t2.serial_no <= t.serial_no and
t2.sale_id <> t.sale_id
) as grp
from taple t
) t
group by grp;
If you only care about sale_id = 1 then put a where clause in the middle subquery query.
Here is a SQL Fiddle.