Representing Unicode String Literals in SQL and PL/SQL

There are three ways to represent a Unicode string literal in SQL or PL/SQL:

• N'string'

  Example: N'résumé'.

  Limitations: See "Avoiding Data Loss During Character-Set Conversion".

• NCHR(number)

  The SQL function NCHR returns the character whose binary equivalent is number in the national character set. The character returned has data type NVARCHAR2.

  Example: NCHR(36) represents $ in the default national character set, AL16UTF16.

  Limitations: Portability of the value of NCHR(number) is limited to applications that use the same national character set.

• UNISTR('string')

  The SQL function UNISTR converts string to the national character set.

  For portability and data preservation, Oracle recommends that string contain only ASCII characters and Unicode encoding values. A Unicode encoding value has the form \xxxx, where xxxx is the hexadecimal value of a character code value in UCS-2 encoding format.

  Example: UNISTR('G\0061ry') represents 'Gary'

  ASCII characters are converted to the database character set and then to the national character set. Unicode encoding values are converted directly to the national character set.