Try this:
SELECT
o.orderid,
o.userid,
MAX(CASE WHEN c.Name = 'CPU' THEN oc.Value END) AS 'CPU',
MAX(CASE WHEN c.Name = 'Motherboard' THEN oc.Value END) AS 'Motherboard',
MAX(CASE WHEN c.Name = 'Memory' THEN oc.Value END) AS 'Memory'
FROM orders o
INNER JOIN ordercomponents oc ON c.orderid = oc.orderId
INNER JOIN Components c ON oc.componentid = c.componentid
GROUP BY o.orderid, o.userid
Note that: This the standard SQL way to do this. But you can use the SQL Server PIVOT
table operator to do the same thing like so:
SELECT *
FROM
(
SELECT o.orderid, o.userid, c.Name 'Name', oc.value 'value'
FROM orders o
INNER JOIN ordercomponent oc ON o.orderid = oc.orderId
INNER JOIN Components c ON oc.componentid = c.componentid
) t
PIVOT
(
MAX(value)
FOR Name IN ([CPU], [Motherboard], [Memory])
) p;
But this for a set of pre defined values like [CPU], [Motherboard], [Memory]
.
For unknown number of values, you have to do it dynamically like so:
DECLARE @cols AS NVARCHAR(MAX);
DECLARE @query AS NVARCHAR(MAX);
select @cols = STUFF((SELECT distinct ',' + QUOTENAME(c.name)
from Components c
FOR XML PATH(''), TYPE
).value('.', 'NVARCHAR(MAX)')
,1,1,'')
set @query = 'SELECT orderid, userid ' + @cols + ' from
(
select o.orderid, o.userid, c.Name Name, oc.value value
FROM orders o
INNER JOIN ordercomponent oc ON o.orderid = oc.orderId
INNER JOIN Components c ON oc.componentid = c.componentid
) x
pivot
(
max(value)
for name in (' + @cols + ')
) p '
execute(@query);