T-SQL Cursor in stored procedure - sql-server

Question

I am using a stored procedure and I want to use cursor for inserting new data (if data exist I want to update)
ALTER Procedure [dbo].[conn]
#ResellerID int,
#GWResellerID int,
#UserName varchar(50),
#Password varchar(50),
#URL varchar(100),
#ServiceType int,
#ServiceDesc varchar(50),
#FeedFrom bit,
#PublicKey varchar(max)
AS
declare gateway cursor for
select *
from reseller_profiles
where main_reseller_ID = #ResellerID
OPEN gateway
FETCH NEXT FROM gateway INTO #ResellerID
WHILE ##FETCH_STATUS = 0
BEGIN
INSERT INTO [dbo].tblGatewayConnection([ResellerID],[GWResellerID], [UserName], [Password], [URL], [ServiceType], [ServiceDesc],[feedFromMain], publicKey)
VALUES (#ResellerID, #GWResellerID, #UserName, #Password, #URL, #ServiceType, #ServiceDesc, #FeedFrom, #PublicKey)
FETCH NEXT FROM gateway INTO #ResellerID
END
CLOSE gateway
DEALLOCATE gateway
My table name is tblGatewayConnection has these columns:
resellerID
gwResellerID
userName
password
url
serviceType
serviceDesc
feedFromMain
publicKey
While I insert data using the stored procedure, I get an exception
Cursorfetch: The number of variables declared in the INTO list must match that of selected columns.
What did I miss ?
Any help will be appreciated.
Thanks.

Answer 1

Why even bother with a cursor?!?!?!?!? I won't tell you what's wrong with your cursor - because instead of fixing the cursor, you should learn to avoid it in the first place!
Seriously - avoid RBAR (row-by-agonizing-row) processing whenever you can, and here, it's really utterly pointless to use a cursor - just use this nice and clean set-based statement:
ALTER PROCEDURE [dbo].[conn] #ResellerID INT,
#GWResellerID INT,
#UserName VARCHAR(50),
#Password VARCHAR(50),
#URL VARCHAR(100),
#ServiceType INT,
#ServiceDesc VARCHAR(50),
#FeedFrom BIT,
#PublicKey VARCHAR(max)
AS
INSERT INTO dbo.tblGatewayConnection
(ResellerID, GWResellerID, UserName, Password,
URL, ServiceType, ServiceDesc, feedFromMain,
publicKey)
SELECT
ResellerID, GWResellerID, UserName, Password,
URL, ServiceType, ServiceDesc, feedFromMain,
publicKey
FROM
dbo.reseller_profiles
WHERE
main_reseller_ID = #ResellerID
and you're done!! No messy cursor, no unnecessary local variables - just a simple INSERT ... SELECT and you've achieved what you want!

Answer 2

I am not sure the error message could be any more self explanatory:
Cursorfetch: The number of variables declared in the INTO list must match that of selected columns.
You are selecting all the columns from reseller_profiles
declare gateway cursor for
select *
from reseller_profiles
where main_reseller_ID = #ResellerID
And trying to put them into a single variable:
FETCH NEXT FROM gateway INTO #ResellerID
The number of columns you select in your cursor must match the number of variables you are inserting to, so you would need something like
declare gateway cursor for
select reseller_id
from reseller_profiles
where main_reseller_ID = #ResellerID
HOWEVER you should not be using a cursor for this, you can use the same thing using INSERT .. SELECT:
INSERT INTO [dbo].tblGatewayConnection
( [ResellerID],[GWResellerID], [UserName], [Password], [URL],
[ServiceType], [ServiceDesc],[feedFromMain], publicKey
)
SELECT Resellerid, #GWResellerID, #UserName, #Password,
#URL, #ServiceType, #ServiceDesc, #FeedFrom, #PublicKey
FROM reseller_profiles
WHERE main_reseller_ID = #ResellerID;
As has been said, you should avoid cursors at all costs, if you absolutely have to use a cursor, declare the most light weight cursor you can. In your case for example, you were only moving forwards within the cursor, only reading data, not modifying it, and only accessing the cursor locally, therefore you would declare the cursor as follows:
DECLARE gateway CURSOR LOCAL STATIC FAST_FORWARD
FOR
SELECT ...
FROM ..
Although cursors perform terribly at the best of times they are given an even worse reputation by lazy declarations.
Finally, You should get out of the habit of using SELECT *