Transpose row into columns with If statement - sql

Question

I am trying to transpose certain row values into columns. Below is what my table looks like:
ID Item Color Quantity
1 Shoe Red
1 Shirt 3
1 Hat Black
1 Socks 2
1 Pants Red
What I want the table to look like is this:
ID Shoe Shirt Hat Socks Pants
1 Red 3 Black 2 Red
Below is the code I am using:
select Max(Case When [Item] = 'Shoe' Then Color End) as Shoe
,Max(Case When [Item] = 'Shirt' Then Quantity End) as Shirt
,Max(Case When [Item] = 'Hat' Then Color End) as Hat
,Max(Case When [Item] = 'Socks' Then Quantity End) as Socks
,Max(Case When [Item] = 'Pants' Then Color End) as Pants
From Inventory
The problem with my code is sometimes the value for the row is in column Color and other times it's in column Quantity. I would like to be able to use only to column with a value. My real select statement has over 50 Max(Case) statements, so if there is someway I can do an overarching if statement and not have to do one for each line that would be great!

Answer 1

If you want a dynamic version.
In the sub-query below, you'll notice that we use CONCAT(), which will handle NULL values appropriately.
Declare #Filter varchar(100) = 'Shoe,Socks'
Declare #SQL varchar(max)
Select #SQL = 'Select ID,' + '['+Replace(#Filter,',','],[')+']' + '
From (
Select ID
,Item
,Value = concat(NullIf(Color,''''),NullIf(Quantity,0))
From Inventory
Where charindex('',''+Item+'','','','+#Filter+','')>0
) A
Pivot (max(Value) For Item in (' + '['+Replace(#Filter,',','],[')+']' + ') ) p'
Exec(#SQL);
EDIT:
Added NullIf() to the concat() to trap "empty" values.

Answer 2

How about using a common table expression (CTE) to find the non null value column then PIVOT on the Item if you know all of your Items up front. It should be noted that this only works if the other value is null, otherwise you would need to check for '' or 0.
;WITH CTE
AS
(
SELECT ID, Item, COALESCE(Color, CAST(Quantity AS VARCHAR(10))) AS Value
FROM Inventory
)
select * from CTE
pivot (max (Value) for Item in ([Shoe],[Shirt],[Hat],[Socks],[Pants])) AS c

Answer 3

You probably need a dictionary which maps an item to a value column. For example
select Max(Case When [Item] = 'Shoe' Then
Case col when 'Color' then Color else Quantity End
End) as Shoe
,Max(Case When [Item] = 'Shirt' Then
Case col when 'Color' then Color else Quantity End
End) as Shirt
,Max(Case When [Item] = 'Hat' Then
Case col when 'Color' then Color else Quantity End
End) as Hat
,Max(Case When [Item] = 'Socks' Then
Case col when 'Color' then Color else Quantity End
End) as Socks
,Max(Case When [Item] = 'Pants' Then
Case col when 'Color' then Color else Quantity End
End) as Pants
From (
select i.*, col
from Inventory i
join (
values ('Shoe', 'Color')
,('Shirt', 'Quantity')
,('Hat', 'Color')
,('Socks', 'Quantity')
,('Pants', 'Color')
) dict (itm, col) on dict.itm=t.item
) t