You use the CHARACTERSET keyword to specify to SQL*Loader which character set is used in each datafile. Different datafiles can be specified with different character sets. However, only one character set can be specified for each datafile.
Using the CHARACTERSET keyword causes character data to be automatically converted when it is loaded into the database. Only CHAR, DATE, and numeric EXTERNAL fields are affected. If the CHARACTERSET keyword is not specified, then no conversion occurs.
The CHARACTERSET syntax is as follows:
CHARACTERSET char_set_name