SQL Azure - Create complex Pivot Table - sql

Question

This question is all for SQL Azure. I have a data set for various commodity prices by year and a unit price like:
Rice - 2007 - 0.5
Rice - 2007 - 0.3
Rice - 2007 - 0.8
Wheat - 2006 - 1.1
Wheat - 2006 - 1.4
etc
How can I create a pivot table that gives me the MAX and MIN price paid for each year for each commodity? I know how to do a pivot table that would give me something like the average - thats pretty easy. But I need my "main" pivot column to be the year and then each year would have its 2 "sub columns" for a MIN and MAX price and I'm not quite sure how to do that. Help!

Answer 1

Unless I am missing something in your explanation, you can do this easily without the PIVOT function:
select product,
year,
min(price) MinPrice,
max(price) MaxPrice
from yourtable
group by product, year
See SQL Fiddle with Demo.
If you want the data in separate columns, then there are a few ways that you can do this.
Aggregate function with CASE:
select product,
min(case when year=2006 then price else 0 end) [2006_MinPrice],
max(case when year=2006 then price else 0 end) [2006_MaxPrice],
min(case when year=2007 then price else 0 end) [2007_MinPrice],
max(case when year=2007 then price else 0 end) [2007_MaxPrice]
from yourtable
group by product
See SQL Fiddle with Demo
UNPIVOT and PIVOT:
The UNPIVOT is used to transform your column data into rows. Once in the rows, you can create the new columns with the year and then pivot:
select *
from
(
select product,
cast(year as varchar(4))+'_'+col as piv_col,
value
from
(
select product,
year,
min(price) MinPrice,
max(price) MaxPrice
from yourtable
group by product, year
) x
unpivot
(
value for col in (minPrice, maxPrice)
) u
) d
pivot
(
max(value)
for piv_col in ([2006_MinPrice], [2006_MaxPrice],
[2007_MinPrice], [2007_MaxPrice])
) piv;
See SQL Fiddle with Demo. These give the result:
| PRODUCT | 2006_MINPRICE | 2006_MAXPRICE | 2007_MINPRICE | 2007_MAXPRICE |
---------------------------------------------------------------------------
| Rice | 0 | 0 | 0.3 | 0.8 |
| Wheat | 1.1 | 1.4 | 0 | 0 |
If you have an unknown number of years, then you coul also implement dynamic sql.