Oracle SQL: the Essential Reference

VSIZE

VSIZE(expr)

Returns the size, in bytes, of the value's internal representation.

Examples

SQL> SELECT VSIZE(SYSDATE) FROM dual;

VSIZE(SYSDATE)
--------------
             8

SQL> SELECT VSIZE(username) FROM dba_users;

VSIZE(USERNAME)
---------------
              3
              6
              5