ROWIDTONCHAR converts a rowid value to NVARCHAR2 datatype. The result of this conversion is always in the national character set and is 18 characters long.
The following example converts a rowid value to an NVARCHAR2 string:
SELECT LENGTHB( ROWIDTONCHAR(ROWID) ), ROWIDTONCHAR(ROWID)
FROM employees;
LENGTHB(ROWIDTONCHAR(ROWID)) ROWIDTONCHAR(ROWID
---------------------------- ------------------
36 AAAFfIAAFAAAABSAAA
. . .