using temp tables in SQL Azure

Question

I am writing a query to pivoting table elements where column name is generated dynamically.

SET @query = N'SELECT STUDENT_ID, ROLL_NO, TITLE, STUDENT_NAME, EXAM_NAME, '+
            @cols +
            ' INTO ##FINAL 
            FROM
            (
                SELECT  *
                FROM #AVERAGES
                UNION 
                SELECT  *
                FROM #MARKS 
                UNION
                SELECT  *
                FROM #GRACEMARKS
                UNION
                SELECT  *
                FROM #TOTAL
                ) p
                PIVOT
                (
                MAX([MARKS])
                FOR SUBJECT_ID IN
                ( '+
                @cols +' )
            ) AS FINAL
            ORDER BY STUDENT_ID ASC, DISPLAYORDER ASC, EXAM_NAME ASC;'

EXECUTE(@query) 

select * from ##FINAL 

This query works properly in my local database, but it doesn't work in SQL Azure since global temp tables are not allowed there.

Now if i change ##FINAL to #FINAL in my local database, but it gives me error as

Invalid object name '#FINAL' .

How can I resolve this issue?

Answer 1

Okay, after saying I didn't think it could be done, I might have a way. It's ugly though. Hopefully, you can play with the below sample and adapt it to your query (without having your schema and data, it's too tricky for me to attempt to write it):

declare @cols varchar(max)
set @cols = 'object_id,schema_id,parent_object_id'

--Create a temp table with the known columns
create table #Boris (
    ID int IDENTITY(1,1) not null
)
--Alter the temp table to add the varying columns. Thankfully, they're all ints.
--for unknown types, varchar(max) may be more appropriate, and will hopefully convert
declare @tempcols varchar(max)
set @tempcols = @cols
while LEN(@tempcols) > 0
begin
    declare @col varchar(max)
    set @col = CASE WHEN CHARINDEX(',',@tempcols) > 0 THEN SUBSTRING(@tempcols,1,CHARINDEX(',',@tempcols)-1) ELSE @tempcols END
    set @tempcols = CASE WHEN LEN(@col) = LEN(@tempcols) THEN '' ELSE SUBSTRING(@tempcols,LEN(@col)+2,10000000) END
    declare @sql1 varchar(max)
    set @sql1 = 'alter table #Boris add [' + @col + '] int null'
    exec (@sql1)
end

declare @sql varchar(max)
set @sql = 'insert into #Boris (' + @cols + ') select ' + @cols + ' from sys.objects'
exec (@sql)

select * from #Boris

drop table #Boris

They key is to create the temp table in the outer scope, and then inner scopes (code running within EXEC statements) have access to the same temp table. The above worked on SQL Server 2008, but I don't have an Azure instance to play with, so not tested there.

Answer 2

If you create a temp table, it's visible from dynamic sql executed in your spid, if you create the table in dynamic sql, it's not visible outside of that.

There is a workaround. You can create a stub table and alter it in your dynamic sql. It requires a bit of string manipulation but I've used this technique to generate dynamic datasets for tsqlunit.

CREATE TABLE #t1 
(
    DummyCol int
)

EXEC(N'ALTER TABLE #t1 ADD  foo INT')

EXEC ('insert into #t1(DummyCol, foo)
VALUES(1,2)')

EXEC ('ALTER TABLE #t1 DROP COLUMN DummyCol')

select *from #t1