Error when compile PLSQL migrated from Oracle 7.3.4 to 9i


I got the following error when compile PLSQL migrated from Oracle 7.3.4 to 9i:
error message: ORA-00918: column ambiguously defined

Does anyone know there are any syntax difference (SQL, PLSQL, datatype etc.)between Oracle 7.3.4 and 9i ?

What are they and how can I fix it ?


Thanks a lot for your help !!!