<< Setting the NLS_COMP Parameter | Setting the NLS_LENGTH_SEMANTICS Parameter >>

Using Length Semantics

Establishing a Globalization Support Environment

Working in a Global Environment 6-25

Set

NLS_COMP

back to its original setting listed in Step 1. For example:

ALTER SESSION SET NLS_COMP=BINARY;

Using Case-Insensitive and Accent-Insensitive Search

Operations inside a database are sensitive to the case and the accents of the characters.
Sometimes, you might need to perform case-insensitive or accent-insensitive
comparisons. Use the

NLS_SORT

session parameter to specify a case-insensitive or

accent-insensitive sort.

To specify a case-insensitive or accent-insensitive sort:

Append

_CI

to an Oracle sort name for a case-insensitive sort. For example:

BINARY_CI

: accent-sensitive and case-insensitive binary sort

GENERIC_M_CI

: accent-sensitive and case-insensitive

GENERIC_M

sort

Append

_AI

to an Oracle sort name for an accent-insensitive and case-insensitive

sort. For example:

BINARY_AI

: accent-insensitive and case-insensitive binary sort

FRENCH_M_AI

: accent-insensitive and case-insensitive

FRENCH_M

sort

Using Length Semantics

In single-byte character sets, the number of bytes and the number of characters in a
string are the same. In multibyte character sets, a character or code point consists of
one or more bytes. Calculating the number of characters based on byte length can be
difficult in a variable-width character set. Calculating column length in bytes is called
byte semantics, while measuring column length in characters is called character
semantics.

Character semantics is useful to define the storage requirements for multibyte strings
of varying widths. For example, in a Unicode database (AL32UTF8), suppose that you
need to define a

VARCHAR2

column that can store up to five Chinese characters

together with five English characters. Using byte semantics, this column requires 15
bytes for the Chinese characters, which are 3 bytes long, and 5 bytes for the English

See Also:

Oracle Database Reference for more information on the

NLS_COMP

parameter.

Using the NLS_SORT Parameter

on page 6-22

Using Case-Insensitive and Accent-Insensitive Search

page 6-25

Oracle Database Globalization Support Guide for a complete
discussion of linguistic sort and string searching