select * from nls_database_parameters where parameter like '%CHARACTERSET';

PARAMETER                      VALUE
------------------------------ 
----------------------------------------------------------------------------------------------------
--------------------
NLS_CHARACTERSET               UTF8
NLS_NCHAR_CHARACTERSET         UTF8

ORA-12899: value too large for column %s (actual: %s, maximum: %s)
 *Cause: An attempt was made to insert or update a column with a value
         which is too wide for the width of the destination column.
         The name of the column is given, along with the actual width
         of the value, and the maximum allowed width of the column.
         Note that widths are reported in characters if character length
         semantics are in effect for the column, otherwise widths are
         reported in bytes.
 *Action: Examine the SQL statement for correctness.  Check source
          and destination column data types.
          Either make the destination column wider, or use a subset
          of the source column (i.e. use substring).