Thanks to Tim for reminding me what a headache this can be!
I'm guilty of creating SQL statements like so:
SELECT testfield FROM sometable
Today that caused a real problem. An error that was incredibly difficult to find.
The error message was:
11 >= 11 null
Seriously, that was the error message displayed by Coldfusion.
The answer was that we should've qualified the table name like so:
SELECT testfield FROM [sometable]
You can take it a step further and do this for your columns as well. I usually do not qualify my column names unless it's necessary, but qualifying your table name is easy and may save your hair.