Issue adding order by to PIVOT group by SQL - sql-server

Question

The SQL Below works gr8, but the order, how to set that to put Jan, Feb, Mar order. I realize I need to do this with ordinal month but when I add in the order by I get error 'The ORDER BY clause is invalid in views, inline functions, derived tables, subqueries, and common table expressions, unless TOP, OFFSET or FOR XML is also specified.'
The results look like :
DECLARE #cols AS NVARCHAR(MAX)
DECLARE #query AS NVARCHAR(MAX)
SET #cols = STUFF((SELECT distinct ',' + QUOTENAME(year(TransactionDateTime))
FROM Quotations
FOR XML PATH(''), TYPE
).value('.', 'NVARCHAR(MAX)')
,1,1,'')
SET #query =
'SELECT *
FROM (
SELECT
left(datename(month,TransactionDateTime),3) as [month], year(TransactionDateTime) as [year],
isnull(count(*),0) as Total
FROM quotations
group by left(datename(month,TransactionDateTime),3), year(TransactionDateTime)
) as s
PIVOT
(
SUM(Total)
FOR [year] IN (' + #cols + ')
) AS QuotationResults'
EXECUTE(#query)

Answer 1

As the error says, you can't order a subquery unless there is a reason for the order (TOP, FOR XML etc). The reason for this is that just because you have ordered the subquery there is no reason that this order would be maintained in your outer query. SQL Server is essentially telling you that your ORDER BY is pointless, therefore not valid.
The solution is to simply add a column with month number to your subuquery s, then you can order by it. You would also need to explicitly state your select list to ensure that this new column does not appear in it:
DECLARE #cols AS NVARCHAR(MAX);
DECLARE #query AS NVARCHAR(MAX);
SET #cols = STUFF((SELECT distinct ',' + QUOTENAME(year(TransactionDateTime))
FROM Quotations
FOR XML PATH(''), TYPE
).value('.', 'NVARCHAR(MAX)')
,1,1,'');
SET #query =
'SELECT [month], ' + #Cols + '
FROM (
SELECT
left(datename(month,TransactionDateTime),3) as [month],
datepart(month,TransactionDateTime) as [monthNum],
year(TransactionDateTime) as [year],
isnull(count(*),0) as Total
FROM quotations
group by left(datename(month,TransactionDateTime),3), datepart(month,TransactionDateTime), year(TransactionDateTime)
) as s
PIVOT
(
SUM(Total)
FOR [year] IN (' + #cols + ')
) AS QuotationResults
ORDER BY QuotationResults.MonthNum;';
EXECUTE(#query);
ADDENDUM
The ISNULL() does not trap the null values because at the point of using ISNULL() they don't exist. COUNT(*) will never return null, so your ISNULL() is actually redundant.
In a very simple example if you have:
TransactionDateTime
----------------------
2015-01-01
2015-02-01
2015-02-01
2014-03-01
To skip ahead one step, after your pivot you will end up with:
Month 2014 2015
------------------------
Jan NULL 1
Feb NULL 2
Mar 1 NULL
So you end up with NULL values, now to go back a step, if you look at the results after your aggregation you have:
Month MonthNum Year Total
-----------------------------------
Jan 1 2015 1
Feb 2 2015 2
Mar 3 2014 1
So there are no rows for Jan or Feb in 2014, therefore SUM(NULL) will yield NULL. I would suggest leaving all the aggregation to the pivot function. So your non dynamic query would look something like:
SELECT pvt.[Month], pvt.[2014], pvt.[2015]
FROM ( SELECT [Month] = LEFT(DATENAME(MONTH, TransactionDateTime), 3),
[MonthNum] = DATEPART(MONTH, TransactionDateTime),
[Year] = DATEPART(YEAR, TransactionDateTime),
Value = 1
FROM Quotations
) AS t
PIVOT
(
COUNT(Value)
FOR [year] IN ([2014], [2015])
) AS pvt
ORDER BY pvt.MonthNum;
And put into dynamic SQL:
DECLARE #cols AS NVARCHAR(MAX);
DECLARE #query AS NVARCHAR(MAX);
SET #cols = STUFF((SELECT DISTINCT ',' + QUOTENAME(DATEPART(YEAR, TransactionDateTime))
FROM Quotations
FOR XML PATH(''), TYPE
).value('.', 'NVARCHAR(MAX)')
,1,1,'');
SET #query =
'SELECT pvt.[Month], ' + #cols + '
FROM ( SELECT [Month] = LEFT(DATENAME(MONTH, TransactionDateTime), 3),
[MonthNum] = DATEPART(MONTH, TransactionDateTime),
[Year] = DATEPART(YEAR, TransactionDateTime),
Value = 1
FROM Quotations
) AS t
PIVOT
(
COUNT(Value)
FOR [year] IN (' + #cols + ')
) AS pvt
ORDER BY pvt.MonthNum;
(
SUM(Total)
FOR [year] IN (' + #cols + ')
) AS QuotationResults
ORDER BY QuotationResults.MonthNum;';
EXECUTE sp_executesql #query;