A. Use the RAISERROR command with the following criteria :-

1. Run ISQL with the -b option
2. Set the message severity to greater than 10
3. Set the message state to 127

i.e.

isql -E -Q"RAISERROR ('set errorlevel 11',11,127)" -b
if errorlevel 11 goto failed

Note that also you need to be running the SQL 6.5 SP5a version of ISQL.EXE. Microsoft broke the returning of error information under certain circumstances and didn't make the fix public until this release.