I have a table called "PROD_COST" with 5 columns:
+----+----------+------+-----------+-------------+
| ID | Duration | Cost | COST_NEXT | COST_CHANGE |
+----+----------+------+-----------+-------------+
- Duration = number of days the price is valid (1 day=1row).
- Cost = product price in this day.
- -Cost_next = lead(cost,1,0).
- Cost_change = Cost_next – Cost.
I need an extra column called "Groups" for aggregation:
+----+----------+------+-----------+-------------+--------+
| ID | Duration | Cost | Next_Cost | Cost_change | Groups |
+----+----------+------+-----------+-------------+--------+
| 1 | 1 | 10 | 8,5 | -1,5 | 1 |
| 2 | 1 | 8,5 | 12,2 | 3,7 | 2 |
| 3 | 1 | 12,2 | 5,3 | -6,9 | 3 |
| 4 | 1 | 5,3 | 4,2 | 1,2 | 4 |
| 5 | 1 | 4,2 | 6,2 | 2 | 4 |
| 6 | 1 | 6,2 | 9,2 | 3 | 4 |
| 7 | 1 | 9,2 | 7,5 | -2,7 | 5 |
| 8 | 1 | 7,5 | 6,2 | -1,3 | 5 |
| 9 | 1 | 6,2 | 6,3 | 0,1 | 6 |
| 10 | 1 | 6,3 | 7,2 | 0,9 | 6 |
| 11 | 1 | 7,2 | 7,5 | 0,3 | 6 |
| 12 | 1 | 7,5 | 0 | 7,5 | 6 |
+----+----------+------+-----------+-------------+--------+
Now I need to group the "Groups" column by Cost_change. It can be positive,negative or 0 values. I was advised to use this code:
select
id, COST_CHANGE, sum(GRP) over (order by id asc) +1
from
(
select
*,
case when sign(COST_CHANGE) != sign(isnull(lag(COST_CHANGE)
over (order by id asc),COST_CHANGE)) and Cost_change!=0 then 1 else 0 end as GRP
from
PROD_COST
) X
But there is a problem: If there are 0 values between two positive or negative values than it groups it separately, for example:
+-------------+--------+
| Cost_change | Groups |
+-------------+--------+
| 9.262 | 5777 |
| -9.262 | 5778 |
| 9.262 | 5779 |
| 0.000 | 5779 |
| 9.608 | 5780 |
| -11.231 | 5781 |
| 10.000 | 5782 |
+-------------+--------+
I need to have:
+-------------+--------+
| Cost_change | Groups |
+-------------+--------+
| 9.262 | 5777 |
| -9.262 | 5778 |
| 9.262 | 5779 |
| 0.000 | 5779 |
| 9.608 | 5779 | -- Here
| -11.231 | 5780 |
| 10.000 | 5781 |
+-------------+--------+
I would be very grateful for any help.
Best Answer
I use your code and added some checks, regarding the
COST_CHANGE = 0
For
Sql Server 2012
, you can use theLAG
(this is not available in 2008,2008R2)--for SQL 2012
--for SQL 2008,2008R2:
The output: