NLS (NATIONAL LANGUAGE SUPPORT) in SQL

 NLS 

(national language support)

nls_sort and nls_comp are parameters used to 
control the sorting and comparison behaviour of
characters in SQL queries. 

1. NLS_SORT:-
binary-binary sorting (ascii)
french-french linguistic sorting.
german-german linguistic sorting.
spanish-spanish linguistic sorting
binary_ci-binary sorting with case-insensitivity.
french_ci-french linguistic sorting with case-insensitivity.
example:-
alter session set nls_sort='FRENCH';

2. NLS_COMP:-
binary-binary comparison (case-sensitive).
linguistic- linguistic comparison(case-insensitive).
example:-
alter session set nls_comp='LINGUISTIC';

overall best for case-insensitive search in SQL oracle:-

alter session set nls_sort='binary_ci';

alter session set nls_comp='linguistic';

select * from nls_database_parameters;

select * from nls_instance_parameters;

select * from nls_session_parameters;