NLS_COMP

Property	Description
Parameter type	String
Syntax	`NLS_COMP = { BINARY \| LINGUISTIC \| ANSI }`
Default value	`BINARY`
Modifiable	`ALTER SESSION`
Basic	No

NLS_COMP specifies the collation behavior of the database session.

Values:

BINARY

Normally, comparisons in the WHERE clause and in PL/SQL blocks is binary unless you specify the NLSSORT function.
LINGUISTIC

Comparisons for all SQL operations in the WHERE clause and in PL/SQL blocks should use the linguistic sort specified in the NLS_SORT parameter. To improve the performance, you can also define a linguistic index on the column for which you want linguistic comparisons.
ANSI

A setting of ANSI is for backwards compatibility; in general, you should set NLS_COMP to LINGUISTIC