This Oracle tutorial explains how to use the Oracle/PLSQL DECOMPOSE function.
DECOMPOSE(x)
function decomposes the string into the same character set
as x and converts x to a Unicode string.
The syntax for the Oracle/PLSQL DECOMPOSE function is:
DECOMPOSE( string )
string
is the string that will be decomposed.
SQL> select decompose('') from dual;
D
-
SQL>