TSQL Cursor calls Stored Procedure 'View Nesting Level Exceeded' - sql

Question

Being a bit of a SQL Newb, I tried to create a SQL script to execute a stored procedure on a number of rows using a cursor. I found the code to create the cursor and the stored procedure works as expected.
However, sometimes during execution I get the error
Maximum stored procedure, function, trigger, or view nesting level exceeded (limit 32)
Here is the SQL script in question. Any ideas why I get this error?
CREATE PROCEDURE p_MigrateRenewalOptions
AS
BEGIN
-- SET NOCOUNT ON added to prevent extra result sets from
-- interfering with SELECT statements.
SET NOCOUNT ON;
DECLARE #OrderId VARCHAR(255) = NULL
DECLARE #RenewalId INT = 0
DECLARE #DiscountCode VARCHAR(255) = NULL
DECLARE #UpgradeCode VARCHAR(255) = NULL
DECLARE #ProductCode VARCHAR(255) = NULL
DECLARE rCursor CURSOR FOR
SELECT RenewalId FROM t_Renewals WHERE DiscountCode IS NOT NULL AND UpgradeCode IS NOT NULL
OPEN rCursor
FETCH NEXT FROM rCursor INTO #RenewalId
-- Iterate over t_Renewals with DiscountCode, UpgradeCode
WHILE ##FETCH_STATUS = 0
BEGIN
SELECT #OrderId = OrderId from t_Renewals where RenewalId = #RenewalId
SELECT #DiscountCode = DiscountCode from t_Renewals where RenewalId = #RenewalId
SELECT #UpgradeCode = UpgradeCode from t_Renewals where RenewalId = #RenewalId
SELECT #ProductCode = ProductCode from t_Order Where OrderId = #OrderId
-- Create renewal options for the t_Renewal entry
EXEC p_SelectOrCreateRenewalOptions #OrderId
-- Migrate the DiscountCode, UpgradeCode from the renewal record
UPDATE t_Renewal_Option
SET CouponCode = #DiscountCode
WHERE RenewalId = #RenewalId AND OptionType = 0 AND CouponCode IS NULL
UPDATE t_Renewal_Option
SET CouponCode = #UpgradeCode
WHERE RenewalId = #RenewalId AND OptionType = 1 AND CouponCode IS NULL
-- NULL the Renewal record DiscountCode, UpgradeCode
UPDATE t_Renewals
SET DiscountCode = NULL, UpgradeCode = NULL
WHERE RenewalId = #RenewalId
FETCH NEXT FROM rCursor INTO #RenewalId
END
CLOSE rCursor
DEALLOCATE rCursor
END
GO
One thing I noted, that the statement
-- Create renewal options for the t_Renewal entry
EXEC p_SelectOrCreateRenewalOptions #OrderId
returns a set, e.g. if you run this code outside of a stored procedure, inside SQL Server Management Studio, you get several sets of results in the output window. Is this the cause? Is it possible to dump the data as I don't need the returned rows from p_SelectOrCreateRenewalOptions
EDIT: As requested, here is the code for p_SelectOrCreateRenewalOptions
CREATE PROCEDURE p_SelectOrCreateRenewalOptions
(
#OrderId VARCHAR(255) = NULL
)
AS
BEGIN
SET NOCOUNT ON
DECLARE #ProductCode VARCHAR(255);
SELECT #ProductCode = ProductCode FROM t_Order WHERE OrderId = #OrderId;
DECLARE #StaticOptionCount INT;
SET #StaticOptionCount = dbo.f_QueryRenewalOptionCount(#ProductCode);
DECLARE #OptionCount INT;
SELECT #OptionCount = COUNT(*) FROM t_Renewal_Option ro INNER JOIN t_Renewals r ON r.RenewalId = ro.RenewalId WHERE r.OrderId = #OrderId
IF (#OptionCount != #StaticOptionCount)
BEGIN
SET TRANSACTION ISOLATION LEVEL SERIALIZABLE
BEGIN TRANSACTION
SELECT #OptionCount = COUNT(*) FROM t_Renewal_Option ro INNER JOIN t_Renewals r ON r.RenewalId = ro.RenewalId WHERE r.OrderId = #OrderId
IF (#OptionCount != #StaticOptionCount)
BEGIN
DECLARE #RenewalId INT;
SELECT #RenewalId = RenewalId FROM t_Renewals r WHERE r.OrderId = #OrderId;
DELETE FROM t_Renewal_Option WHERE RenewalId = #RenewalId;
INSERT INTO t_Renewal_Option (RenewalId, OptionProductCode, OptionType, LastUpdated)
SELECT #RenewalId, sro.OptionProductCode, sro.OptionTypeId, GETDATE()
FROM t_Static_Renewal_Option sro
WHERE sro.ProductCode = #ProductCode
END
COMMIT TRANSACTION
END
SELECT ro.* FROM t_Renewal_Option ro INNER JOIN t_Renewals r ON r.RenewalId = ro.RenewalId WHERE r.OrderId = #OrderId
END
GO
f_QueryRenewalOptionCount simply does a select:
-- f_QueryRenewalOptionCount
SELECT #Count = COUNT(*) FROM t_Static_Renewal_Option o WHERE o.ProductCode = #ProductCode
Triggers wise, I don't think we have any triggers. There is a trigger on the t_Order table on INSERT but apart from that, nothing else.
UPDATE 12-SEP-14:
This 'works' but I don't understand the problem fully. I wrapped the EXEC call into a Begin/End Transaction
Note this script is called once to migrate some old part of the schema to a new part. Its not performance intensive and just has to 'work once'

Answer 1

Do you have a trigger on any of your tables? If an update trigger updates its own table, it will trigger itself again, which will update the table again, etc.
Do you use view or function anywhere in your code? Views can call on other views or functions, which call other views / functions.

Answer 2

The cursor here, while makes my skin crawl, is likely not the cause of the error your seeing. Without being able to see what the nested stored procedure is doing, this is just an educated guess, but that's probably where the issue lies.
The error you're seeing happens whenever a recursive SQL operation basically gets stuck in an infinite loop. The two ways I have had it happen is with a poorly written recursive CTE (basically a table which infinitely unions to itself) or when, as is more likely in this case, a store procedure calls a stored procedure which calls a stored procedure... and so on down the line. For instance (and I haven't tested this) if p_selectOrCreateRenewalOptions called p_MigrateRenewalOptions, you'd probably see a similar error.