ORA-01722 with Full Table Scan

My application developers approached me with an issue which is very unique to me. They were complaining about a query which was failing with ORA-01722 “invalid number” after an upgrade to 11.1.0.7 from 10.2.0.4. The syntax of the query is like: select max(a) from t1 where c1<>'abc' and c2=12345 and c3='Y' and c4='xyz'; This query…