Note: Microsoft Books online is a default reference of all articles but examples and explanations prepared by Ritesh Shah, founder of http://www.SQLHub.com
I have written many articles on PIVOT even I feel to write one more on practical situation. Suppose you have one table which contain studentID, year of student, total marks, increase and decrease. We need to find list of student on increase and decrease. How can we do that?
Have a look at this example with dummy data.
CREATE TABLE StudDetail
INSERT INTO StudDetail
SELECT 1, ’08-09′, 3333,0,0 union all
SELECT 1, ’09-10′, 4252,25,0 union all
SELECT 2, ’08-09′, 2100,0,0 union all
SELECT 2, ’09-10′, 2002,0,-10
SELECT * from (select StudentID,PassYear,grades FROM StudDetail where increase>=0) up
PIVOT (sum(grades) for passyear in ([08-09], [09-10])) AS pivo
–I can work with above query but what if I don’t know how much year I have to make column???
–I have to go for dynamic query, let us create it.
–START creating dynamic code for PIVOT
DECLARE @Cols NVARCHAR(2000)
–make column list for PIVOT
SELECT @Cols=@Cols+ ‘[‘+s.Passyear +‘]’+ ‘, ‘ FROM
(SELECT DISTINCT PassYear FROM StudDetail) AS s
–remove last comma from column list
–create pivot query as we have just added distinct year list in @Cols variable
SET @Cols=‘SELECT * from (select StudentID,PassYear,grades FROM StudDetail where increase>=0) up
PIVOT (sum(grades) for passyear in (‘+@cols+‘)) AS pivo’
–print query and check
EXECUTE sp_executeSQL @Cols
Sometime we may need to see some data of one column as a column header and aggregated results in those columns as a data. There are many programmatic ways to cater this need. Herewith, I am going to explained Fixed Column Cross Tab results with PIVOT. I will write few more articles for other ways of doing the same task.
Here is the table, I will be using for demo.
Create Table SalesSummaryOfRegions
Item VARCHAR(10) NOT NULL,
State VARCHAR(10) NOT NULL,
TotalSales INT NOT NULL
INSERT INTO SalesSummaryOfRegions
SELECT ‘LAPTOP’,‘CA’,100 UNION ALL
SELECT ‘LAPTOP’,‘NJ’,1200 UNION ALL
SELECT ‘ADAPTER’,‘CA’,910 UNION ALL
SELECT ‘MOUSE’, ‘NY’,1100 UNION ALL
Now, I want to get list of all the Items of NJ and CA with its total and average sales. It seems quiet easy as we can use simple GROUP BY clause and SUM aggregate function. But what if I want to see four column named Item, CA, NJ, Average.
Item column should contain all the Items we used to sell. CA column contain total of each item we sold in CA state in respective item’s row and same with NJ. Average column should contain average of particular item sold for both the state. Not you can say, its bit challenging. Yes, it is, if you are going to do it with sub query logic or cursor. But with the help of PIVOT in Microsoft SQL Server 2005, it is very simple. Have a look at following query.
SELECT Item,CA,NJ,(isnull(CA,0)+isnull(NJ,0))/2 as ‘Average’ FROM SalesSummaryOfRegions
sum(TotalSales) FOR state in (CA,NJ)
In above query, we gave Item from SalesSummaryOfRegions table in select list but we don’t have CA and NJ column in our table. Rest assure, it won’t show you error as it was not written by mistake, it’s a use of PIVOT. You can see I use one aggregate function after PIVOT words in above query and it was used for state column. As will be showing average also, so there is one possibility of NULL value as respective value so I want to make sure that NULL value will be treated as 0 that is why I have used isnull() function.
Reference: Ritesh Shah