Using oracle bind variables in sqlplus

SQL> desc emp
 名称                                                                                    是否为空? 类型
 ----------------------------------------------------------------------------------------- -------- ------------------------------------------------------------
 EMPNO											   NOT NULL NUMBER(4)
 ENAME												    VARCHAR2(10)
 JOB												    VARCHAR2(9)
 MGR												    NUMBER(4)
 HIREDATE											    DATE
 SAL												    NUMBER(7,2)
 COMM												    NUMBER(7,2)
 DEPTNO 											    NUMBER(2)


SQL> variable empno number;  
SQL> exec :empno:=7844;

PL/SQL 过程已成功完成。

SQL> select * from emp where empno = :empno; 

     EMPNO ENAME			  JOB				     MGR HIREDATE	     SAL       COMM	DEPTNO
---------- ------------------------------ --------------------------- ---------- ------------ ---------- ---------- ----------
      7844 TURNER                         SALESMAN                          7698 08-9月 -81         1500                    30