We don't always get enough information when an exception happens to track down where the issue is.
It would be helpful if the tablename and/or the SQL statement was also displayed to help track down problems.
When trying to load a fixture file I was receiving the following:
SQLSTATE: Integrity constraint violation: 1048 Column 'created_at' cannot be null
As you can see - it doesn't help much as it doesn't display the table/class that's the created_at column is on.
As quick fix - I modified the rethrowException method in Doctrine_Connection to include some information from the invoker (not a great fix - I should really dig deeper and see if there's a __toString() method on classes that can be passed as the invoker):