Last updated: 17-Nov-2008

When exporting/importing one can minimize risk of losing data during import/export by setting NLS_LANG.

– Before starting export set NLS_LANG to be the same character set of the database being exported which means no conversion takes place, all the data will be stored in the export file as it was stored in the database.
– Before starting import set NLS_LANG to be the same value as the it was set during export which means no conversion will take place in the import session, but if the character set of the target database is different the data will automatically be converted when import inserts the data in the database.

OR

– Before starting export set NLS_LANG to be the same character set of the database being imported to which means conversion takes place at this step it will automatically convert during export.
– Before starting import set NLS_LANG to be the same value as the it was set during import which means no conversion will take place as it was already converted during export.

To find the NLS_LANG click on the following link