Oracle PL/SQL之不能在function里面调用DBMS_LOCK（Grant to role OR Grant to user）

已知：测试用户tuser1，测试角色trole1，trole1已经授权给了tuser1。

在测试一段程序时需要用到延时，于是就把dbms_lock授权给了trole1，放在匿名块里测试没有问题：

SQL> set serveroutput on;
SQL>
SQL> BEGIN
2    dbms_output.put_line(systimestamp);
3    --  dbms_backup_restore.sleep(3);
4    dbms_lock.sleep(3);
5    dbms_output.put_line(systimestamp);
6  END;
7  /

24-JUN-11 04.30.57.722000000 PM +08:00
24-JUN-11 04.31.00.723000000 PM +08:00

PL/SQL procedure successfully completed

SQL>

但是把它移到function里面却报错了：

Connected to Oracle Database 11g Enterprise Edition Release 11.2.0.1.0
Connected as tuser1

SQL>
SQL> CREATE OR REPLACE FUNCTION sum2(p_deptno IN NUMBER) RETURN NUMBER IS
2    l_ret NUMBER;
3  BEGIN
4    dbms_lock.sleep(5);
5    SELECT SUM(sal)
6    INTO   l_ret
7    FROM   emp
8    WHERE  deptno = p_deptno;
9    RETURN l_ret;
10  END sum2;
11  /

Warning: Function created with compilation errors

SQL> show err;
Errors for FUNCTION TUSER1.SUM2:

LINE/COL ERROR
-------- --------------------------------------------------
4/3      PLS-00201: identifier 'DBMS_LOCK' must be declared
4/3      PL/SQL: Statement ignored

很奇怪，难道不能在function里面用dbms_lock，google一下，找到答案：

必须把dbms_lock的execute权限直接grant给用户才行，只grant给角色就会报错。

REF：http://forums.oracle.com/forums/thread.jspa?threadID=902392&tstart=0&messageID=3481832

现在function可以正常创建了，不过为什么呢？怎么会存在grant to user和grant to role在某些object上有区别？

SQL>
SQL> CREATE OR REPLACE FUNCTION sum2(p_deptno IN NUMBER)
2    RETURN NUMBER IS PRAGMA AUTONOMOUS_TRANSACTION;
3  l_ret NUMBER;
4  BEGIN
5    dbms_lock.sleep(5);
6    --DBMS_BACKUP_RESTORE.SLEEP(5);
7    dbms_output.put_line(systimestamp);
8    SELECT SUM(sal)
9    INTO   l_ret
10    FROM   emp
11    WHERE  deptno = p_deptno;
12    RETURN l_ret;
13  END sum2;
14  /

Function created

SQL>