SQL Server 2008 R2: Pivot table query performance - sql

Question

Table: Product
create table Product
(
productID int,
productName varchar(20),
productsalesdate DATETIME,
producttype varchar(20)
);
Insertion:
insert into product values(1,'PenDrive','2010-01-01','Electronic');
insert into product values(1,'Computer','2016-01-01','Electronic');
insert into product values(1,'Laptop','2011-02-02','Electronic');
insert into product values(2,'textbook','2014-02-02','books');
insert into product values(2,'notebook','2016-01-01','books');
insert into product values(3,'Car','2016-01-01','Vehicle');
insert into product values(3,'Bike','2016-01-07','Vehicle');
First Try: In this I am getting wrong sum of productType
SELECT productID, FirstSale,LastSale, [Electronic],[books],[Vehicle]
FROM
(
SELECT
productID,
MIN(ProductSalesdate) as FirstSale,
MAX(ProductSalesdate) as LastSale,
productType
FROM
Product
Group by productID,productType
) a
PIVOT
(
COUNT(productType)
FOR productType IN ( [Electronic],[books],[Vehicle] )
) AS pvt;
Second Try: In this try I have solved the sum problem but the query is taking more time for execute for huge records.
SELECT productID,FirstSale,LastSale ,[Electronic],[books],[Vehicle]
FROM
(
SELECT a.ProductID, a.FirstSale, a.LastSale, b.ProductType
FROM Product b
inner join
(
SELECT
productID,
MIN(ProductSalesdate) as FirstSale,
MAX(ProductSalesdate) as LastSale
FROM
Product
Group by productID
) as a
ON a.ProductID = b.ProductID
) ab
PIVOT
(
COUNT(productType)
FOR productType IN ( [Electronic],[books],[Vehicle] )
) AS pvt;
Note: The second query is works fine but the problem is with the performance, because of
I am joining two same table because to get count of productType in the pivot query.
Question: How to optimize the second query which is a my second try?

Answer 1

The following uses a temporary table to store the derived table ab. My guess is it will improve the execution plan of the second query.
SELECT a.ProductID, a.FirstSale, a.LastSale, b.ProductType
INTO #ab
FROM Product b
inner join
(
SELECT
productID,
MIN(ProductSalesdate) as FirstSale,
MAX(ProductSalesdate) as LastSale
FROM
Product
Group by productID
) as a
ON a.ProductID = b.ProductID;
SELECT productID,FirstSale,LastSale ,[Electronic],[books],[Vehicle]
FROM #ab AS ab
PIVOT
(
COUNT(productType)
FOR productType IN ( [Electronic],[books],[Vehicle] )
) AS pvt;
DROP TABLE #ab;
EDIT: Just for sports I wrote following script which has 15k rows in #product. The whole script executes in ~1 second. I still don't understand how your query takes 5.5 minutes. Here goes:
SET NOCOUNT ON;
CREATE TABLE #product (
product_id INT,
product_name VARCHAR(20),
product_sales_date DATE,
product_type VARCHAR(20)
);
DECLARE #cnt INT=0;
WHILE #cnt<15000
BEGIN
INSERT INTO #product(
product_id,
product_name,
product_sales_date,
product_type
)
SELECT
product_id=ROUND(20*RAND(),0),
product_name=LEFT(NEWID(),20),
product_sales_date=DATEADD(DAY,ROUND((-10+20*RAND()), 0),GETDATE()),
product_type=
CASE ROUND(2*RAND(),0)
WHEN 0 THEN 'Electronic'
WHEN 1 THEN 'books'
ELSE 'Vehicle'
END;
SET #cnt=#cnt+1;
END
SELECT a.product_id, a.first_sale, a.last_sale, b.product_type
INTO #ab
FROM #product b
inner join
(
SELECT
product_id,
MIN(product_sales_date) as first_sale,
MAX(product_sales_date) as last_sale
FROM
#product
GROUP BY
product_id
) as a
ON a.product_id= b.product_id;
SELECT product_id,first_sale,last_sale,[Electronic],[books],[Vehicle]
FROM #ab AS ab
PIVOT
(
COUNT(product_type)
FOR product_type IN ( [Electronic],[books],[Vehicle] )
) AS pvt;
DROP TABLE #ab;
DROP TABLE #product;

Answer 2

Seems like you're trying to do something like this.. Not sure why you'd need extra joins or temp tables..
SELECT * FROM
(
SELECT productID,
productType,
MIN(ProductSalesdate) as FirstSale,
MAX(ProductSalesdate) as LastSale,
COUNT(productType) AS ProductCount
FROM Product
GROUP BY productID,productType
) t
PIVOT
(
SUM(ProductCount)
FOR productType IN ([Electronic],[books],[Vehicle])
) p
you'll get NULLS for the 0 counts but you can coalesce those values to 0 pretty easily