IF EXISTS with SQL Server 2008 - sql-server-2008

Question

I have a table order in which there are 3 columns
BookCode Quantity Billno
--------------------------
Ed001 2 A1
Ed002 3 A1
Ed003 1 A1
py001 5 A2
ed001 1 A2
ed005 2 A2
ed003 4 A2
Now I want to show my result to user as
table Result
BookCode A1 A2
----------------------
Ed001 2 1
Ed002 3 0
Ed003 1 4
py001 0 5
ed005 0 1
Result is my temporary table, I alter it and add column according to Billno
this works fine
Now I select BookCode and Quantity from table Order and insert it into result
What I want that if there is already a bookcode exist then just update result table otherwise insert a new row with that bookcode.
What should I do for that?

Answer 1

I solved it using Cursor..
create table #Result(BookCode varchar(20),BookRate float)
create table #bill(bilno varchar(max) )
insert into #bill ('A1')
insert into #bill ('A2')
SET #Ordnum = CURSOR FOR
SELECT bilno FROM #bill
OPEN #Ordnum
FETCH NEXT
FROM #Ordnum INTO #billno
WHILE ##FETCH_STATUS = 0
BEGIN
EXEC ('ALTER TABLE #temp ADD [' + #billno+ '] varchar(30)')
SET #getbookcode = CURSOR FOR
SELECT BookCode , BookQuantity , BookRate FROM OrderDetail where BillNo = #billno
OPEN #getbookcode
FETCH NEXT
FROM #getbookcode INTO #Tbookcode,#TbookQty,#TbookRate
WHILE ##FETCH_STATUS = 0
BEGIN
if exists(select BookCode from #Result where BookCode = #Tbookcode and BookRate = #TbookRate)
begin
EXEC('Update #Result set [' + #billno+']= '+#TbookQty+' where BookCode = '''+#Tbookcode+''' and BookRate = '+#TbookRate+'')
end
else
begin
EXEC('Insert Into #Result ([' + #bno + '],BookCode,BookRate) values ( '+#TbookQty +' , '''+#Tbookcode+''','+#TbookRate+')')
end
FETCH NEXT FROM #getbookcode INTO #Tbookcode,#TbookQty , #TbookRate
END
CLOSE #getbookcode
DEALLOCATE #getbookcode
FETCH NEXT FROM #Ordnum INTO #bno
END
CLOSE #Ordnum
DEALLOCATE #Ordnum
select * from #Result
Here #bill is a Temporary table in which Billnum are stored.

Answer 2

Use the MERGE statement. This does an INSERT or UPDATE based on the matching
Something like this, which includes the PIVOT needed
MERGE INTO result R
USING (
SELECT
ISNULL(O1.BookCode, O2.BookCode) AS BookCode,
ISNULL(O1.Quantity, 0) AS A1,
ISNULL(O2.Quantity, 0) AS A2
FROM
(SELECT * FROM #ORDER WHERE BillNo = 'A1') O1
FULL OUTER JOIN
(SELECT * FROM #ORDER WHERE BillNo = 'A2') O2
ON O1.BookCode = O2.BookCode
) src ON R.BookCode = src.BookCode
WHEN MATCHED THEN
UPDATE
SET A1 = src.A1, A2 = src.A2
WHEN NOT MATCHED BY TARGET THEN
INSERT (BookCode, A1, A2)
VALUES (src.BookCode, src.A1, src.A2);