DROP PRCOEDURE问题，奇怪了..,

DECLARE
    AN_FLAG NUMBER;
BEGIN
    SELECT COUNT(1)
      INTO AN_FLAG
        FROM ALL_OBJECTS
     WHERE OBJECT_TYPE = 'PROCEDURE'
       AND OWNER = 'XX用户'
       AND OBJECT_NAME = 'P_test';
    IF AN_FLAG > 0 THEN
        EXECUTE IMMEDIATE 'DROP PRCOEDURE db_user.P_test';
    END IF;
END;

报错：ORA-00950: 无效 DROP 选项
======
DBA用户了,DROP ANY PROCEDURE权限也有，莫名奇妙，不是这样写吗? DROP?PRCOEDURE 无效?DROP?选项
[解决办法]
db_user是什么???