´øÄãÉîÈëÁ˽âOracleÖм¸¸öÏà¶ÔÌØÊâµÄº¯Êý

SQL> select TO_SINGLE_BYTE('£ï£ò£á£ã£ì£å') from dual;

TO_SINGLE_BYTE('£Ï£Ò£Á£Ã£Ì£Å')
------------------------------
oracle

SQL> select to_char(to_date('12345','J'),'Jsp') en from dual;

en
----------------------------------------
Twelve Thousand Three Hundred Forty-Five

²»¹ýÓÐÏÞÖÆ£ºÒ»Êdz¤¶ÈµÄÏÞÖÆ£¬¶þÊDz»ÄÜת»»´øСÊýµÄ

SQL> select to_char(to_date('88888882345','J'),'Jsp') from dual;

select to_char(to_date('88888882345','J'),'Jsp') from dual

ORA-01854: julian ÈÕÆÚ±ØÐë½éÓÚ 1 ºÍ 5373484 Ö®¼ä 

julian dateÖ¸µÄÊǹ«ÔªÇ°4712Äê1ÔÂ1ÈÕÆð¾­¹ýµÄÌìÊý.

the inner TO_CHAR simply converts the number 
(which would probably be a numeric variable in practice) 
to CHAR so some magic can happen ... 

the TO_DATE converts the CHAR using the J (Julian day) 
format. (the Julian day is the number of days since 
January 1, 4712BC, which is when SQL*Plus was invented), 

having established the date value, we then convert that 
date back to a Julian day. Because the TO_CHAR in this 
case is used in DATE context, we can use the J mask to 
duplicate the original value, and append the SP (spell) 
format mask. 'Spell" does exactly that - it converts the 
number to words, hence the string value above. 
SP can be used in a number of situations. For example, 
if SYSDATE is 26-AUG-98, then : 

SELECT TO_CHAR ( SYSDATE, 'DdSp') FROM dual; -- spells 
the day as Twenty-Six, 
and 
SELECT TO_CHAR ( SYSDATE, 'DDSPTH') FROM dual; 
--returns TWENTY-SIXTH