语法：VSIZE（字符串）

例：显示正好为5个字符的员工的姓名

SCOTT@itkaifang> select empno,ename from emp where vsize(ename)=5;
     EMPNO ENAME
---------- ----------
      7369 SMITH
      7499 ALLEN
      7566 JONES
      7698 BLAKE
      7782 CLARK
      7788 SCOTT
      7876 ADAMS
      7900 JAMES
8 rows selected.
SCOTT@itkaifang>