When an error stops execution in SQL Server? - sql-server

Question

If I exec this batch:
begin transaction
PRINT 'start'
PRINT 1/0
PRINT 'continue'
drop table dbo.tblPrueba
select * from dbo.tblPrueba
PRINT 'finish'
rollback transaction
The ouput is this:
start
Msg 8134, Level 16, State 1, Line 3
Divide by zero error encountered.
continue
Msg 208, Level 16, State 1, Line 6
Invalid object name 'dbo.tblPrueba'.
I am forcing two errors:
- the first one: PRINT 1/0 (that generates this error:
Msg 8134, Level 16, State 1, Line 3
Divide by zero error encountered.
) And continue executing the batch
- the second one:
drop table dbo.tblPrueba
select * from dbo.tblPrueba
That generates this error:
Msg 208, Level 16, State 1, Line 6
Invalid object name 'dbo.tblPrueba'.
And stops execution of the batch
What is the different between them? Where can I learn those that stop execution and those that doesn´t?
Thanks a lot!!

Answer 1

Since the first error is a divide by zero error, this behavior depends on your ARITHABORT, ARITHIGNORE and ANSI_WARNINGS settings.
From the article:
These three SET commands give you very fine-grained control for a very
small set of errors. When a division by zero or an overflow occurs,
there are no less four choices.
No action at all, result is NULL – when ARITHIGNORE is ON.
Warning message, result is NULL – when all are OFF.
Statement-termination – when ANSI_WARNINGS is ON.
Batch-abortion – when ARITHABORT is ON and ANSI_WARNINGS is OFF.
As far as which errors stop execution and which ones don't, please refer to the same article.

Answer 2

The easiest way to ensure all errors are handled correctly is to use TRY/CATCH
Without this, different errors can be statement, scope or batch aborting depending on settings such as ARITHxx, ANSI_WARNINGS and XACT_ABORT. This is demonstrated and discussed at "Error Handling in SQL 2000"
You can see the different (no SET options changed) with this
CREATE TABLE dbo.tblPrueba (gbn int);
GO
BEGIN TRY
begin transaction
PRINT 'start'
PRINT 1/0
PRINT 'continue'
drop table dbo.tblPrueba
select * from dbo.tblPrueba
PRINT 'finish'
rollback transaction
END TRY
BEGIN CATCH
SELECT ERROR_MESSAGE();
IF XACT_STATE() <> 0 rollback transaction
END CATCH
If I run this twice, I get this because the DROP is never executed
Msg 2714, Level 16, State 6, Line 1
There is already an object named 'tblPrueba' in the database.

Answer 3

Where can I learn those that stop execution
You can use exception handling
Begin try
begin transaction
PRINT 'start'
PRINT 1/0
PRINT 'continue'
create table #t
(
id int
)
drop table #t
select * from #t
PRINT 'finish'
rollback transaction
End Try
Begin Catch
if( XACT_STATE() == 1)
Rollback Tran
End Catch
You can use Set XACT_ABORT ON like below.
Set XACT_ABORT ON
begin transaction
PRINT 'start'
PRINT 1/0
PRINT 'continue'
create table #t
(
id int
)
drop table #t
select * from #t
PRINT 'finish'
rollback transaction