While importing tables from Oracle database, Sometimes I am getting java.lang.IllegalArgumentException: Attempted to generate class with no columns! or NullPointerException what might be the root cause and fix for this error scenario?

While dealing with Oracle database from Sqoop, Case sensitivity of table names and user names matters highly. Most probably by specifying these two values in UPPER case will solve the issue unless actual names are mixed with Lower/Upper cases. If these are mixed, then we need to provide them within double quotes.

In case, the source table is created under different user namespace, then we need to provide table name as USERNAME.TABLENAME as shown below.

MySQL

sqoop import \
--connect jdbc:oracle:thin:@oracle.example.com/ORACLE \
--username SQOOP \
--password sqoop \
--table DP.EMPLOYEES