SQL Server - multiple rows into one

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

您可以通过将表重新连接几次来实现此目的，但这可能是性能问题。

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