COMPOSE

Syntax

Description of the illustration compose.gif

Purpose

COMPOSE takes as its argument a string, or an expression that resolves to a string, in any datatype, and returns a Unicode string in its fully normalized form in the same character set as the input. char can be any of the datatypes CHAR, VARCHAR2, NCHAR, NVARCHAR2, CLOB, or NCLOB. For example, an o code point qualified by an umlaut code point will be returned as the o-umlaut code point.

CLOB and NCLOB values are supported through implicit conversion. If char is a character LOB value, it is converted to a VARCHAR value before the COMPOSE operation. The operation will fail if the size of the LOB value exceeds the supported length of the VARCHAR in the particular development environment.

Examples

The following example returns the o-umlaut code point:

SELECT COMPOSE ( 'o' || UNISTR('\0308') ) FROM DUAL; 

CO 
-- 
ö