I have follwing data :
Product Price StartDate EndDate
Apples 4.9 2010-03-01 00:00:00.000 2010-03-01 00:00:00.000
Apples 4.9 2010-03-02 00:00:00.000 2010-03-02 00:00:00.000
Apples 2.5 2010-03-03 00:00:00.000 2010-03-03 00:00:00.000
Apples 4.9 2010-03-05 00:00:00.000 2010-03-05 00:00:00.000
Apples 4.9 2010-03-06 00:00:00.000 2010-03-06 00:00:00.000
Apples 4.9 2010-03-09 00:00:00.000 2010-03-09 00:00:00.000
Apples 2.5 2010-03-10 00:00:00.000 2010-03-10 00:00:00.000
Apples 4.9 2010-03-11 00:00:00.000 2010-03-11 00:00:00.000
Apples 4.9 2010-03-12 00:00:00.000 2010-03-12 00:00:00.000
Apples 4.9 2010-03-13 00:00:00.000 2010-03-13 00:00:00.000
Apples 4.9 2010-03-15 00:00:00.000 2010-03-15 00:00:00.000
Apples 4.9 2010-03-16 00:00:00.000 2010-03-16 00:00:00.000
want to group like product, price, min(startdate), max(startdate) but should have grouping in start date and end date as well........ something like below
Desired result
Apples 4.9 2010-03-01 00:00:00.000 2010-03-02 00:00:00.000
Apples 2.5 2010-03-03 00:00:00.000 2010-03-03 00:00:00.000
Apples 4.9 2010-03-05 00:00:00.000 2010-03-09 00:00:00.000
Apples 2.5 2010-03-10 00:00:00.000 2010-03-10 00:00:00.000
Apples 4.9 2010-03-11 00:00:00.000 2010-03-16 00:00:00.000
My approach.
Data:
create table t ( producte varchar(50),
price money,
start_date date,
end_date date);
insert into t values
( 'apple', 4.9, '2012-01-01', '2012-01-01' ),
( 'apple', 4.9, '2012-01-02', '2012-01-02' ),
( 'apple', 8, '2012-01-04', '2012-01-04' ),
( 'cat', 5, '2012-01-01', '2012-01-01' ),
( 'cat', 6, '2012-01-02', '2012-01-02' ),
( 'cat', 6, '2012-01-03', '2012-01-03' );
Query:
with start_dates as (
select
t.producte, t.price, t.start_date, t.end_date, t.start_date as gr_date
from
t left outer join
t t1 on
t.price = t1.price and --new
t.producte = t1.producte and
t.start_date = dateadd(day,1, t1.end_date )
where t1.producte is null
union all
select
t.producte, t.price, t.start_date,t. end_date, gr_date
from
t inner join
start_dates t1 on
t.price = t1.price and --new
t.producte = t1.producte and
t.start_date = dateadd(day,1, t1.end_date )
)
select t.producte, t.price , min( t.start_date ), max( t.end_date )
from start_dates t
group by t.producte, gr_date ,t.price
| PRODUCTE | PRICE | COLUMN_2 | COLUMN_3 |
----------------------------------------------
| apple | 4.9 | 2012-01-01 | 2012-01-02 |
| apple | 8 | 2012-01-04 | 2012-01-04 |
| cat | 5 | 2012-01-01 | 2012-01-01 |
| cat | 6 | 2012-01-02 | 2012-01-03 |
Explanation
This is a recursive CTE expression. Base query take inital dates for each group of prices. Recursive query looks for last data with this price.
SELECT product, price, MIN(start_date), MAX(end_date)
FROM (
SELECT product, price, start_date, end_date,
ROW_NUMBER() OVER (PARTITION BY product ORDER BY startDate) rn1,
ROW_NUMBER() OVER (PARTITION BY product, price ORDER BY startDate) rn2
FROM mytable
) q
GROUP BY
product, price, rn2 - rn1
ORDER BY
product, MIN(start_date), price
Here is a SQLFiddle demo
with t2 as
(
select t1.*,
(select count(Price)
from t
where startdate<t1.startdate
and Price<>t1.price
and Product=t1.Product
)
rng
from t as t1
)
select Product,Price,min(startDate),max(EndDate)
from t2 group by Product,Price,RNG
order by 3
Here's a suggestion: for each row, you must find the maximum previous date for which the price is different and you Group on that. For example, for any line between 2010-03-11 and 2010-03-16, you must retrieve the date 2010-03-10 because this is the maximum previous date for which the price is different (2.5 versus 4.9). The first row(s) will return a null date but that shouldn't be a problem.
However, for a very long table, this kind of query could become very slow. Therefore, if you have some speed problem, you should look into the possibility of adding a column and use a cursor to fill it incrementally: you loop through it by date and each time you see a new price, you change its value. The final Grouping is then trivial.
Here's something:
Select Product, Price, Min(StartDate) as StartDate, PreviousDate from (
Select product, price, StartDate, (Select max (StartDate) from table_2 t3 where t3.price <> t2.price and t3.StartDate < t2.StartDate and t3.Product = t2.Product) as previousDate
from table_2 t2) SQ
Group by Product, Price, PreviousDate
Order by PreviousDate
I believe this is the best-performing solution so far:
WITH Calc AS (
SELECT *,
Grp = DateAdd(day, -Row_Number()
OVER (PARTITION BY Product, Price ORDER BY StartDate), StartDate
)
FROM dbo.PriceHistory
)
SELECT Product, Price, FromDate = Min(StartDate), ToDate = Max(StartDate)
FROM Calc
GROUP BY Product, Price, Grp
ORDER BY FromDate;
来源：https://stackoverflow.com/questions/14020981/t-sql-multiple-grouping