RPAD(str,len,padstr)

返回字符串str，右填充以字符串str中垫到len字符长度。如果str为大于len，返回值被缩短至len个字符。

SQL> SELECT RPAD('hi',5,'?');
+---------------------------------------------------------+
| RPAD('hi',5,'?')                                        |
+---------------------------------------------------------+
| hi???                                                   |
+---------------------------------------------------------+
1 row in set (0.00 sec)