On 3/22/2015 10:48 AM, Bart Smissaert wrote: > But I thought that as the non-aliased column emis_number is in the > sub-select (select emis_number from DIABETICS) > that column name could only apply to the table DIABETICS and there should > be no ambiguity.
A subselect can happily use columns from the containing statement. Read about a "correlated subquery" in your favorite SQL textbook. -- Igor Tandetnik
