SQL Server 2012 Dynamic Pivot with a Join [duplicate] - sql

Question

I have a table of Customers
Customer ID Name
1 John
2 Lewis
3 Mary
I have another table CustomerRewards
TypeID Description
1 Bronze
2 Silver
3 Gold
4 Platinum
5 AnotherOne
And the final table
RewardID TypeID CustomerID
1 1 1
2 1 1
3 2 1
4 2 2
The customerTypes table is dynamic, many of these types can be added and removed. Basically all I want is the columns to be generated dynamically and a count in each, something like
CustomerName Bronze Silver Gold Platinum AnotherOne total
John 2 1 0 0 0 3
Lewis 0 1 0 0 0 1
Grand TOTAL 2 2 0 0 0 4
The problem like I said it that the types are dynamic and the customers are dynamic so I need the columns to be dynamic depending on the types in the system
I have tagged c# as I need this in a DataGridView
Thanks in advance

Answer 1

You will want to use a PIVOT function for this. If you have a known number of columns, then you can hard-code the values:
select name, [Bronze], [Silver], [Gold], [Platinum], [AnotherOne]
from
(
select c.name,
cr.description,
r.typeid
from customers c
left join rewards r
on c.id = r.customerid
left join customerrewards cr
on r.typeid = cr.typeid
) x
pivot
(
count(typeid)
for description in ([Bronze], [Silver], [Gold], [Platinum], [AnotherOne])
) p;
See SQL Fiddle with Demo.
Now if you have an unknown number of columns, then you can use dynamic SQL to PIVOT:
DECLARE #cols AS NVARCHAR(MAX),
#query AS NVARCHAR(MAX)
select #cols = STUFF((SELECT ',' + QUOTENAME(description)
from customerrewards
group by description, typeid
order by typeid
FOR XML PATH(''), TYPE
).value('.', 'NVARCHAR(MAX)')
,1,1,'')
set #query = 'SELECT name,' + #cols + ' from
(
select c.name,
cr.description,
r.typeid
from customers c
left join rewards r
on c.id = r.customerid
left join customerrewards cr
on r.typeid = cr.typeid
) x
pivot
(
count(typeid)
for description in (' + #cols + ')
) p '
execute(#query)
See SQL Fiddle With Demo
If you need to include the Total column, then you can use ROLLUP (Static Version Demo):
select name, sum([Bronze]) Bronze, sum([Silver]) Silver,
sum([Gold]) Gold, sum([Platinum]) Platinum, sum([AnotherOne]) AnotherOne
from
(
select name, [Bronze], [Silver], [Gold], [Platinum], [AnotherOne]
from
(
select c.name,
cr.description,
r.typeid
from customers c
left join rewards r
on c.id = r.customerid
left join customerrewards cr
on r.typeid = cr.typeid
) x
pivot
(
count(typeid)
for description in ([Bronze], [Silver], [Gold], [Platinum], [AnotherOne])
) p
) x
group by name with rollup
Dynamic version (Demo):
DECLARE #cols AS NVARCHAR(MAX),
#colsRollup AS NVARCHAR(MAX),
#query AS NVARCHAR(MAX)
select #cols = STUFF((SELECT ',' + QUOTENAME(description)
from customerrewards
group by description, typeid
order by typeid
FOR XML PATH(''), TYPE
).value('.', 'NVARCHAR(MAX)')
,1,1,'')
select #colsRollup
= STUFF((SELECT ', Sum(' + QUOTENAME(description) + ') as '+ QUOTENAME(description)
from customerrewards
group by description, typeid
order by typeid
FOR XML PATH(''), TYPE
).value('.', 'NVARCHAR(MAX)')
,1,1,'')
set #query
= 'SELECT name, '+ #colsRollup + '
FROM
(
SELECT name,' + #cols + ' from
(
select c.name,
cr.description,
r.typeid
from customers c
left join rewards r
on c.id = r.customerid
left join customerrewards cr
on r.typeid = cr.typeid
) x
pivot
(
count(typeid)
for description in (' + #cols + ')
) p
) x1
GROUP BY name with ROLLUP'
execute(#query)