SQL Server Stored Procedure Error Handling - sql-server

I have a stored procedure which is runs automatically every morning in SQL Server 2008 R2, part of this stored procedure involves executing other stored procedures. The format can be summarised thus:
BEGIN TRY
-- Various SQL Commands
EXECUTE storedprocedure1
EXECUTE storedprocedure2
-- etc
END TRY
BEGIN CATCH
--This logs the error to a table
EXECUTE errortrappingprocedure
END CATCH
storedprocedure1 and storedprocedure2 basically truncate a table and select into it from another table. Something along the lines of:
BEGIN TRY
TRUNCATE Table1
INSERT INTO Table1 (A, B, C)
SELECT A, B, C FROM MainTable
END TRY
BEGIN CATCH
EXECUTE errortrappingprocedure
END CATCH
The error trapping procedure contains this:
INSERT INTO
[Internal].dbo.Error_Trapping
(
[Error_Number],
[Error_Severity],
[Error_State],
[Error_Procedure],
[Error_Line],
[Error_Message],
[Error_DateTime]
)
(
SELECT
ERROR_NUMBER(),
ERROR_SEVERITY(),
ERROR_STATE(),
ERROR_PROCEDURE(),
ERROR_LINE(),
ERROR_MESSAGE(),
GETDATE()
)
99% of the time this works, however occasionally we will find that storedprocedure1 hasn't completed, with Table1 only being part populated. However no errors are logged in our error table. I've tested the error trapping procedure and it does work.
When I later run storedprocedure1 manually it completes fine. No data in the source table will have changed by this point so it's obviously not a problem with the data, something else has happened in that instant which has caused the procedure to fail. Is there a better way for me to log errors here, or somewhere else within the database I can look to try and find out why it is failing?

Try to use SET ARITHABORT (see link). It must ROLLBACK in your case. Also the answer of #Kartic seem reasonable.
I recommned also to read about implicit and explicit transactions - I think that this is your problem. You have several implicit transactions and when error happeneds you are in the middle of the job - so only part is rollbackеd and you have some data in that tables.

There are some type of Errors that TRY..CATCH block will not handle them, look here for more information https://technet.microsoft.com/en-us/library/ms179296(v=sql.105).aspx . for such Errors you should handle them in your application.
also I think you might have transaction management problem in your application too.

I am not sure if I understood you completely. Below code is too big for comment. So posting as an answer for your reference. If this is not what you want, I'll delete it.
Can we add transaction handling part as well.
DECLARE #err_msg NVARCHAR(MAX)
BEGIN TRY
BEGIN TRAN
-- Your code goes here
COMMIT TRAN
END TRY
BEGIN CATCH
SET #err_msg = ERROR_MESSAGE()
SET #err_msg = REPLACE(#err_msg, '''', '''''')
ROLLBACK TRAN
-- Do something with #err_msg
END CATCH

Related

SQL Server stored procedures reading data before insert completed

I'm new to SQL Server and stored procedures and could do with a couple of pointers regarding transaction handling on a bug I've inherited.
I have two stored procedures, one inserts a record passed into it, then it calls another one where the first thing it does is read what was inserted.
But sometimes it completes successfully without processing the data. My suspicion is that the selects are happening before the insert has 'hit' the table and retrieve no records, and the stored procedure doesn't handle that.
I don't have time to re-engineer just yet, but the transaction handling looks suspect. Below is a rough outline of what the stored procedures do.
procedure sp1
(#id, #pbody)
as
begin
begin try
set nocount on;
begin
insert into tbl1 (id, tbody)
values (#id, #pbody)
exec sp2 #id
end
end try
begin catch
execute sperror
end catch
end
go
procedure sp2 (#id)
as
begin
begin try
set nocount on;
declare #vbody varchar(max)
select #vbody = tbody -- I don't believe this step always retrieves the row inserted by sp1
from tbl1 with (nolock)
where id = #id
create table #tmp1 (id, msg)
insert into #tmp1
select id, msg
from openjson........
while exists(select top 1 * from #tmp1) -- this looks similar to above, not sure the insert has finished before the read
begin
** do some stuff **
end
end try
begin catch
execute sperror
end catch
end
go
sp2 is using the WITH (NOLOCK) query hint, which can have unintended side-effects. Missing rows is just one of them.
Using NOLOCK? Here's How You'll Get the Wrong Query Results. - Brent Ozar Unlimited®
I'd strongly recommend removing that hint unless you really understand what it does and have a very good reason for using it.

How can I stop a recordset being returned by a SQL Server stored procedure if an error is encountered after the SELECT

Hoping someone can help. I'm trying to stop a stored procedure from returning a recordset that has been selected, if an error is encountered later in the stored procedure. I've included some pseudo code below to show what I'm doing. Basically, the SELECT [Foo] is returning a recordset if the or COMMIT actions fail and [Tran1] is rolled back. The client does not support multiple recordsets and the has to come after the SELECT so I'm looking for a command to place in the CATCH block that effectively cancels the SELECT [Foo] and instead enables me to return the recordset created by SELECT -1 AS [Error_Code]
BEGIN TRANSACTION [Tran1]
BEGIN TRY
SET NOCOUNT ON;
<Do some Update>
SELECT [Foo]
FROM [Bar]
<Do some Insert>
COMMIT TRANSACTION [Tran1]
END TRY
BEGIN CATCH
ROLLBACK TRANSACTION [Tran1]
SELECT -1 AS Error_Code
END CATCH

SQL Server XACT_ABORT with exclusion

I have a larger stored procedure which utilizes several TRY/CATCH blocks in order to catch and log individual errors. I have also wrapped a transaction around the entire contents of the procedure, so as to be able to roll back the entire thing in the event of an error raised somewhere along the way (in order to prevent a lot of messy cleanup); XACT_ABORT has been enabled since it would otherwise not roll back the entire transaction.
Key component:
There is a table in my database which gets a record inserted each time this procedure is run with the results of operations and details on what went wrong.
Funny thing is happening - actually, when I finally figured out what was wrong, it was pretty obvious... the the insert statement into my log table is getting rolled back as well, hence, if I am not running this out of SSMS, I will not be able to see that this was even run, as the rollback removes all trances of activity.
Question:
Would it be possible to have the entire transaction roll back with the exception of this single insert statement? I would still want to preserve the error message which I compile during the running of the stored procedure.
Thanks so much!
~Eli
Update 6/28
Here's a code sample of what I'm looking at. Key difference between this and the samples posed by #Alex and #gameiswar is that in my case, the try/catch blocks are all nested inside the single transaction. The purpose of this is to have multiple catches (for the multiple tables), though we would the entire mess to be rolled back even if the last update failed.
SET XACT_ABORT ON;
BEGIN TRANSACTION
DECLARE #message AS VARCHAR(MAX) = '';
-- TABLE 1
BEGIN TRY
UPDATE TABLE xx
SET yy = zz
END TRY
BEGIN CATCH
SET #message = 'TABLE 1 '+ ERROR_MESSAGE();
INSERT INTO LOGTABLE
SELECT
GETDATE(),
#message
RETURN;
END CATCH
-- TABLE 2
BEGIN TRY
UPDATE TABLE sss
SET tt = xyz
END TRY
BEGIN CATCH
SET #message = 'TABLE 2 '+ ERROR_MESSAGE();
INSERT INTO LOGTABLE
SELECT
GETDATE(),
#message
RETURN;
END CATCH
COMMIT TRANSACTION
You can try something like below ,which ensures you log the operation.This takes advantage of the fact that table variables dont get rollbacked..
Psuedo code only to give you idea:
create table test1
(
id int primary key
)
create table logg
(
errmsg varchar(max)
)
declare #errmsg varchar(max)
set xact_abort on
begin try
begin tran
insert into test1
select 1
insert into test1
select 1
commit
end try
begin catch
set #errmsg=ERROR_MESSAGE()
select #errmsg as "in block"
if ##trancount>0
rollback tran
end catch
set xact_abort off
select #errmsg as "after block";
insert into logg
select #errmsg
select * from logg
OK... I was able to solve this using a combination of the great suggestions put forth by Alex and GameisWar, with the addition of the T-SQL GOTO control flow statement.
The basic ideas was to store the error message in a variable, which survives a rollback, then have the Catch send you to a FAILURE label which will do the following:
Rollback the transaction
Insert a record into the log table, using the data from the aforementioned variable
Exit the stored procedure
I also use a second GOTO statement to make sure that a successful run will skip over the FAILURE section and commit the transaction.
Below is a code snippet of what the test SQL looked like. It worked like a charm, and I have already implemented this and tested it (successfully) in our production environment.
I really appreciate all the help and input!
SET XACT_ABORT ON
DECLARE #MESSAGE VARCHAR(MAX) = '';
BEGIN TRANSACTION
BEGIN TRY
INSERT INTO TEST_TABLE VALUES ('TEST'); -- WORKS FINE
END TRY
BEGIN CATCH
SET #MESSAGE = 'ERROR - SECTION 1: ' + ERROR_MESSAGE();
GOTO FAILURE;
END CATCH
BEGIN TRY
INSERT INTO TEST_TABLE VALUES ('TEST2'); --WORKS FINE
INSERT INTO TEST_TABLE VALUES ('ANOTHER TEST'); -- ERRORS OUT, DATA WOULD BE TRUNCATED
END TRY
BEGIN CATCH
SET #MESSAGE = 'ERROR - SECTION 2: ' + ERROR_MESSAGE();
GOTO FAILURE;
END CATCH
GOTO SUCCESS;
FAILURE:
ROLLBACK
INSERT INTO LOGG SELECT #MESSAGE
RETURN;
SUCCESS:
COMMIT TRANSACTION
I don't know details but IMHO general logic can be like this.
--set XACT_ABORT ON --not include it
declare #result varchar(max) --collect details in case you need it
begin transaction
begin try
--your logic here
--if something wrong RAISERROR(...#result)
--everything OK
commit
end try
begin catch
--collect error_message() and other into #result
rollback
end catch
insert log(result) values (#result)

Check for Valid XML in SQL Server 2005 trigger

I'm trying to write a INSTEAD OF INSERT trigger that will take a MESSAGE column of type VARCHAR(MAX) and attempt to convert it to XML. If the MESSAGE is not valid XML (malformed), I simply want to pass on the original MESSAGE. If it is valid XML, I want to modify it a bit and then insert the modified version.
My first attempt was to use a TRY/CATCH inside the trigger like this:
BEGIN TRY
SET #Message = (SELECT CONVERT(XML, inserted.[MESSAGE], 1) FROM inserted)
END TRY
BEGIN CATCH
--Cast failed. Insert without XML parsing.
GOTO InsertOriginal
END CATCH
...Perform work on XML and do the insert
Problem is, the failed conversion "dooms" the implied trigger transaction and even though execution runs to completion, the overall transaction fails.
So I then tried this
BEGIN TRANSACTION XmlCastTrans;
BEGIN TRY
SET #Message = (SELECT CONVERT(XML, inserted.[MESSAGE], 1) FROM inserted)
END TRY
BEGIN CATCH
ROLLBACK TRANSACTION XmlCastTrans;
--Cast failed. Insert without XML parsing.
GOTO InsertOriginal
END CATCH
COMMIT TRANSACTION XmlCastTrans;
That doesn't work either, as I get a cannot roll back XmlCastTrans. No transaction or savepoint of that name was found error. How can I get this to work?
This is using SQL Server 2005.
If your XML data is in a predictable format could you consider adding a binding to a schema collection on the XML column to enforce good inserts?
http://technet.microsoft.com/en-us/library/ms176009(v=sql.90).aspx

Ignoring errors in Trigger

I have a stored procedure which is called inside a trigger on Insert/Update/Delete.
The problem is that there is a certain code block inside this SP which is not critical.
Hence I want to ignore any erros arising from this code block.
I inserted this code block inside a TRY CATCH block. But to my surprise I got the following error:
The current transaction cannot be committed and cannot support operations that write to the log file. Roll back the transaction.
Then I tried using SAVE & ROLLBACK TRANSACTION along with TRY CATCH, that too failed with the following error:
The current transaction cannot be committed and cannot be rolled back to a savepoint. Roll back the entire transaction.
My server version is: Microsoft SQL Server 2008 (SP2) - 10.0.4279.0 (X64)
Sample DDL:
IF OBJECT_ID('TestTrigger') IS NOT NULL
DROP TRIGGER TestTrigger
GO
IF OBJECT_ID('TestProcedure') IS NOT NULL
DROP PROCEDURE TestProcedure
GO
IF OBJECT_ID('TestTable') IS NOT NULL
DROP TABLE TestTable
GO
CREATE TABLE TestTable (Data VARCHAR(20))
GO
CREATE PROC TestProcedure
AS
BEGIN
SAVE TRANSACTION Fallback
BEGIN TRY
DECLARE #a INT = 1/0
END TRY
BEGIN CATCH
ROLLBACK TRANSACTION Fallback
END CATCH
END
GO
CREATE TRIGGER TestTrigger
ON TestTable
FOR INSERT, UPDATE, DELETE
AS
BEGIN
EXEC TestProcedure
END
GO
Code to replicate the error:
BEGIN TRANSACTION
INSERT INTO TestTable VALUES('data')
IF ##ERROR > 0
ROLLBACK TRANSACTION
ELSE
COMMIT TRANSACTION
GO
I was going through the same torment, and I just solved it!!!
Just add this single line at the very first step of your TRIGGER and you're going to be fine:
SET XACT_ABORT OFF;
In my case, I'm handling the error feeding a specific table with the batch that caused the error and the error variables from SQL.
Default value for XACT_ABORT is ON, so the entire transaction won't be commited even if you're handling the error inside a TRY CATCH block (just as I'm doing). Setting its value for OFF will cause the transaction to be commited even when an error occurs.
However, I didn't test it when the error is not handled...
For more info:
SET XACT_ABORT (Transact-SQL) | Microsoft Docs
I'd suggest re-architecting this so that you don't poison the original transaction - maybe have the transaction send a service broker message (or just insert relevant data into some form of queue table), so that the "non-critical" part can take place in a completely independent transaction.
E.g. your trigger becomes:
CREATE TRIGGER TestTrigger
ON TestTable
FOR INSERT, UPDATE, DELETE
AS
BEGIN
INSERT INTO QueueTable (Col1,Col2)
SELECT COALESCE(i.Col1,d.Col1),COALESCE(i.Col2,d.Col2) from inserted i,deleted d
END
GO
You shouldn't do anything inside a trigger that might fail, unless you do want to force the transaction that initiated the trigger action to also fail.
This is a very similar question to Why try catch does not suppress exception in trigger
Also see the answer here T-SQL try catch transaction in trigger
I don’t think you can use savepoints inside a trigger. I mean, you can but I googled about it and I saw a few people saying that they don’t work. If you replace your “save transaction” for a begin transaction, it compiles. Of course it is not necessary because you have the outer transaction control and the inner rollback would rollback everything.

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