SQL Server - multiple rows into one - sql

Question

Hope you can help...
I have data table in this format (Lets refer this table as 'Product')
productid property_name property_value last_updated
p0001 type p1 05-Oct-2010
p0001 name Premium 05-Oct-2010
p0001 cost 172.00 05-Oct-2010
p0002 type p3 06-Oct-2010
p0002 name standard 06-Oct-2010
p0002 cost 13.00 06-Oct-2010
*(there are like 50 more properties of which i would need 15 atleast in my query.
However, i just ignore them for this example)*
I would need the data in this format:
productid type name cost
p0001 p1 Premium 172.00
p0002 p3 standard 13.00
I tried with a function and a view to get this format but it takes good few mins to get some 1000 records. Wonder if anyone knows quicker way?
What I tried:
Create function fun1(#productid nvarchar(50)) returns #retdetails table
(
type nvarchar(50) null,
name nvarchar(50) null,
cost nvarchar(50) null,
)
begin
declare
#type nvarchar(50),
#name nvarchar(50),
#cost nvarchar(50),
select #type=property_value from product where productid=#productid and property_name='type';
select #name=property_value from product where productid=#productid and property_name='name';
select #cost=property_value from product where productid=#productid and property_name='cost';
if isnull(#productid,'')<>''
begin
insert #retdetails
select #type, #name, #cost;
end;
return;
end;
then a view
select p.productid, pd.type, pd.name, pd.cost
from (select distinct productid from product) p
cross apply dbo.fun1(p.productid) pd
The slower response might be down to 'distinct' but without that I get duplicate records. I would appreciate any suggestion to get a quickier sql response.
Many Thanks

Answer 1

You could try this PIVOT approach
SELECT productid,
MAX(CASE WHEN property_name = 'type' THEN property_value END) AS type,
MAX(CASE WHEN property_name = 'name' THEN property_value END) AS name,
MAX(CASE WHEN property_name = 'cost' THEN property_value END) AS cost
FROM Product
GROUP BY productid

Answer 2

You could probably do this by joining the table back onto itself a couple of times, might be a bit of a performance issue though.

Answer 3

Starting from SQL Server 2005, you can use PIVOT operator:
DECLARE #TestData TABLE
(
productid VARCHAR(5) NOT NULL
,property_name VARCHAR(5) NOT NULL
,property_value VARCHAR(10)NOT NULL
,last_updated DATETIME NOT NULL
);
INSERT #TestData
SELECT 'p0001','type','p1' ,'05-Oct-2010'
UNION ALL
SELECT 'p0001','name','Premium' ,'05-Oct-2010'
UNION ALL
SELECT 'p0001','cost','172.00' ,'05-Oct-2010'
UNION ALL
SELECT 'p0002','type','p3' ,'06-Oct-2010'
UNION ALL
SELECT 'p0002','name','standard','06-Oct-2010'
UNION ALL
SELECT 'p0002','cost','13.00' ,'06-Oct-2010';
;WITH PivotSource
AS
(
SELECT a.productid
,a.property_name
,a.property_value
FROM #TestData a
)
SELECT pvt.*
--,CONVERT(NUMERIC(8,2), pvt.cost) NumericCost
FROM PivotSource src
PIVOT ( MAX(src.property_value) FOR src.property_name IN ([type], [name], [cost]) ) pvt
Results:
productid type name cost NumericCost
p0001 p1 Premium 172.00 172.00
p0002 p3 standard13.00 13.00