how to check database character set in oracle

Note that database character set refers to the term character set encoding and in oracle database the terms character set and character set encoding are often used interchangeably.
The database character set in oracle determines the set of characters can be stored in the database. It is also used to determine the character set to be used for object identifiers and PL/SQL variables and for storing PL/SQL program source.

The database character set information is stored in the data dictionary tables named SYS.PROPS$.
You can get the character set used in the database by SYS.PROPS$ table or any other views (like database_properties/ nls_database_parameters) exist in the database. The parameter NLS_CHARACTERSET value contains the database character set name. Get it from,

SQL> select value$ from sys.props$ where name='NLS_CHARACTERSET';

VALUE$
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SQL> select property_value from database_properties where property_name=
'NLS_CHARACTERSET';

PROPERTY_VALUE
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SQL> select value from nls_database_parameters where parameter='NLS_CHARACTERSET';

VALUE
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