TSQL error checking code not working - sql

Question

I'm trying to add an alert to my log for a running insert of a view into a table when there is an error executing the query in the view. When I run the view alone, I get an invalid input into SUBSTRING (the exact wording of the error I can't remember). When I run it as part of my view -> table stored procedure, the error is ignored, then I have to go digging for the offending line and make an exception in the view's code to omit that line from the results (I know, it sounds kludge-y, but I'm doing data reduction on huge web-log files from a specialized webapp), but I digress.
I've tried two different methods for trying to catch the error and neither are triggered in such a way to insert the row indicating an error in my execution result table (refresh_results). I think I may be missing some fundamental - perhaps the errors are being encapsulated in come way. If I can't detect the error, the only way to notice an error is if someone notices the number of entries into the table is low for a given period of time.
SELECT #TransactionName = 'tname';
BEGIN TRANSACTION #TransactionName;
BEGIN TRY
print 'tname ***In Try***';
if exists (select name from sysobjects where name='tablename')
begin
drop table tablename;
end
select * into tablename
from opendatasource('SQLNCLI', 'Data Source=DATABASE;UID=####;password=####').dbo.viewname;
COMMIT TRANSACTION #TransactionName;
END TRY
BEGIN CATCH
print 'tablename ***ERROR - check for SUBSTRING***';
begin transaction
set #result_table = 'tablename ***ERROR - check for SUBSTRING***'
select #result_time = getdate(),
#result_rows = count(logtime)
from tablename
insert INTO [dbo].[refresh_results] (result_time, result_table, result_rows)
values (#result_time, #result_table, #result_rows);
commit transaction
ROLLBACK TRANSACTION #TransactionName;
END CATCH
or
if exists (select name from sysobjects where name='tablename')
begin
drop table tablename;
end
select * into tablename
from opendatasource('SQLNCLI', 'Data Source=DATABASE;UID=####;password=####').dbo.viewname;
print '##error'
print ##error
if ##error <> 0
Begin
print 'tablename ***ERROR - check for SUBSTRING***';
set #result_table = 'tablename ***ERROR - check for SUBSTRING***'
select #result_time = getdate(),
#result_rows = count(logtime)
from tablename
insert INTO [dbo].[refresh_results] (result_time, result_table, result_rows)
values (#result_time, #result_table, #result_rows);
End

Answer 1

Your nested transactions aren't doing what you think. You are rolling back the error you thought you stored. Roll back the initial transaction and then, if you feel the need, start a new transaction for logging the error.
See here.

Answer 2

You have two seperate problems
In your first example you are running transactions that do the following:
BEGIN TRAN
...error...
BEGIN TRAN
...log error...
COMMIT TRAN
ROLLBACK TRAN
The inner transaction is rolled back with the outer transaction. Maybe try:
BEGIN TRAN
...error...
ROLLBACK TRAN
BEGIN TRAN
...log error...
ROLLBACK TRAN
The second example you are using ##ERROR. As I understand it as soon as you run something ##ERROR is replaced. That something I think includes the print statement.
If you change it to something like:
DECLARE #Error INT
select * into tablename
from opendatasource('SQLNCLI', 'Data Source=DATA3;UID=;password=').dbo.viewname;
SET #Error = ##ERROR
print '##error'
print #Error
if #Error <> 0
...log the error
The advantage of the TRY CATCH is that if you have an error it will catch it. The ##ERROR method works 100% but it only works on the last line run. so if you have an error with DROP TABLE tablename ##ERROR won't get it (unless you add another check)

Answer 3

Ok, so I had to use a helper procedure to add a log entry. I think what was going on is that the rollback was also rolling back the log entry.
This is what I had to do:
DECLARE #myError tinyint;
BEGIN TRY
BEGIN TRANSACTION;
if exists (select name from sys.sysobjects where name='table_name')
begin
drop table table_name
end
select * into table_name
from opendatasource('SQLNCLI', 'Data Source=###;UID=###;password=###').view_Table
COMMIT TRANSACTION;
END TRY
BEGIN CATCH
set #myError = 1
ROLLBACK TRANSACTION;
END CATCH
if #myError <> 0
begin
exec dbo.table error
end
ELSE
EXEC exec dbo.table normal row