Oracle生成隨機字符串的方法是通過dbms_random.string實現的。
1.dbms_random.string用法
Oracle官方文檔參考鏈接：http://download.oracle.com/docs/cd/B19306_01/appdev.102/b14258/d_random.htm#i996825
用法是DBMS_RANDOM.STRING(選項, 返回字符串長度)
選項有如下幾種可供選擇：
1）'u', 'U' - returning string in uppercase alpha characters
2）'l', 'L' - returning string in lowercase alpha characters
3）'a', 'A' - returning string in mixed case alpha characters
4）'x', 'X' - returning string in uppercase alpha-numeric characters
5）'p', 'P' - returning string in any printable characters.
6）Otherwise the returning string is in uppercase alpha characters.
2.以隨機生成8位密碼這個簡單需求為例演示一下各個選項的用法
1）生成由大寫字母組成的8位密碼
sys@ora10g> select dbms_random.string('u',8) "u_8_password" from dual;
u_8_password
------------------------------------------------------------------
HXGBMNCF
sys@ora10g> select dbms_random.string('U',8) "U_8_password" from dual;
U_8_password
------------------------------------------------------------------
JEZLDJXK
2）生成由小寫字母組成的8位密碼
sys@ora10g> select dbms_random.string('l',8) "l_8_password" from dual;
l_8_password
------------------------------------------------------------------
ilxpvvmy
sys@ora10g> select dbms_random.string('L',8) "L_8_password" from dual;
L_8_password
------------------------------------------------------------------
pzvjvpji
3）生成由大小寫字母混合出現的8位密碼
sys@ora10g> select dbms_random.string('a',8) "a_8_password" from dual;
a_8_password
------------------------------------------------------------------
YfeaneZx
sys@ora10g> select dbms_random.string('A',8) "A_8_password" from dual;
A_8_password
------------------------------------------------------------------
IghqWAVu
4）生成由大寫字母和數字組成的8位密碼
sys@ora10g> select dbms_random.string('x',8) "x_8_password" from dual;
x_8_password
------------------------------------------------------------------
2VKQ4FSH
sys@ora10g> select dbms_random.string('X',8) "X_8_password" from dual;
X_8_password
------------------------------------------------------------------
MMYTPC40
5）生成由任何可打印字符組成的8位密碼
sys@ora10g> select dbms_random.string('p',8) "p_8_password" from dual;
p_8_password
------------------------------------------------------------------
G7`Rbe#V
sys@ora10g> select dbms_random.string('P',8) "P_8_password" from dual;
P_8_password
------------------------------------------------------------------
wPqHt*0.
6）當選項為其他字母的時候返回的內容仍將是大寫字母
選項以“8”為例，返回的8位隨機字符串內容是由大寫字母組成的。
sys@ora10g> select dbms_random.string('8',8) "8_8_password" from dual;
8_8_password
------------------------------------------------------------------
PJGYPPLG
3.小結
本文以具體實例形式演示了dbms_random.string的用法。有時候也可以混合使用。
sys@ora10g> select dbms_random.string('u',8)||dbms_random.string('l',8) "u_l_16_password" from dual;
u_l_16_password
------------------------------------------------------------------
EMVXOZLGixziwvny
Good luck.
參考：http://blog.itpub.net/25746731/viewspace-693735/