How to pivot multiple columns without aggregation - sql

Question

I use SqlServer and i have to admit that i'm not realy good with it ...
This might be and easy question for the advanced users (I hope)
I have two tables which look like this
First table (ID isn't the primary key)
ID IdCust Ref
1 300 123
1 300 124
2 302 345
And the second (ID isn't the primary key)
ID Ref Code Price
1 123 A 10
1 123 Y 15
2 124 A 14
3 345 C 18
In the second table, the column "Ref" is the foreign key of "Ref" in the first table
I'm trying to produce the following output:
[EDIT]
The column "Stock", "Code" and "Price" can have x values, so I don't know it, in advance...
I tried so many things like "PIVOT" but it didn't give me the right result, so i hope someone can solve my problem ...

Answer 1

Use row_number() function and do the conditional aggregation :
select id, IdCust, Ref,
max(case when Seq = 1 then stock end) as [Stock A], -- second table *id*
max(case when Seq = 1 then code end) as [Code 1],
max(case when Seq = 1 then price end) as [Price1],
max(case when Seq = 2 then stock end) as [Stock B], -- second table *id*
max(case when Seq = 2 then code end) as [Code 2],
max(case when Seq = 2 then price end) as [Price2]
from (select f.*, s.Id Stock, s.Code, s.Price,
row_number() over (partition by f.Ref order by s.id) as Seq
from first f
inner join second s on s.Ref = f.Ref
) t
group by id, IdCust, Ref;
However, this would go with known values else you would need go with dynamic solution for that.

Answer 2

#YogeshSharma's provided an excellent answer.
Here's the same done using Pivot; SQL Fiddle Demo.
Functionally there's no difference between the two answers. However, Yogesh's solution's simpler to understand, and performs better; so personally I'd opt for that... I included this answer only because you mention PIVOT in the question:
select ft.Id
, ft.IdCust
, ft.Ref
, x.Stock1
, x.Code1
, x.Price1
, x.Stock2
, x.Code2
, x.Price2
from FirstTable ft
left outer join (
select Ref
, max([Stock1]) Stock1
, max([Stock2]) Stock2
, max([Code1]) Code1
, max([Code2]) Code2
, max([Price1]) Price1
, max([Price2]) Price2
from
(
select Ref
, Id Stock
, Code
, Price
, ('Stock' + cast(Row_Number() over (partition by Ref order by Id, Code) as nvarchar)) StockLineNo
, ('Code' + cast(Row_Number() over (partition by Ref order by Id, Code) as nvarchar)) CodeLineNo
, ('Price' + cast(Row_Number() over (partition by Ref order by Id, Code) as nvarchar)) PriceLineNo
from SecondTable
) st
pivot (max(Stock) for StockLineNo in ([Stock1],[Stock2])) pvtStock
pivot (max(Code) for CodeLineNo in ([Code1],[Code2])) pvtCode
pivot (max(Price) for PriceLineNo in ([Price1],[Price2])) pvtPrice
Group by Ref
) x
on x.Ref = ft.Ref
order by ft.Ref
Like Yogesh's solution, this will only handle as many columns as you specify; it won't dynamically alter the number of columns to match the data. For that you'd need to do dynamic SQL. However; if you need to do that, it's more likely you're attempting to solve the problem in the wrong way... so consider your design / determine if you really need additional columns per result rather than additional rows / some alternate approach...
Here's a Dynamic SQL implementation based on #YogeshSharma's answer: DBFiddle
declare #sql nvarchar(max) = 'select id, IdCust, Ref'
select #sql = #sql + '
,max(case when Seq = 1 then stock end) as [Stock' + rowNumVarchar + ']
,max(case when Seq = 1 then code end) as [Code' + rowNumVarchar + ']
,max(case when Seq = 1 then price end) as [Price' + rowNumVarchar + ']
'
from
(
select distinct cast(row_number() over (partition by ref order by ref) as nvarchar) rowNumVarchar
from second s
) z
set #sql = #sql + '
from (select f.*, s.Id Stock, s.Code, s.Price,
row_number() over (partition by f.Ref order by s.id) as Seq
from first f
inner join second s on s.Ref = f.Ref
) t
group by id, IdCust, Ref;
'
print #sql --see what the SQL produced is
exec (#sql)
(Here's a SQL Fiddle link for this one; but it's not working despite the SQL being valid