带你深入了解Oracle中几个相对特殊的函数

SQL> select TO_SINGLE_BYTE('ｏｒａｃｌｅ') from dual;TO_SINGLE_BYTE('ＯＲＡＣＬＥ')------------------------------oracle

SQL> select to_char(to_date('12345','J'),'Jsp') en from dual;en----------------------------------------Twelve Thousand Three Hundred Forty-Five不过有限制：一是长度的限制，二是不能转换带小数的SQL> select to_char(to_date('88888882345','J'),'Jsp') from dual;select to_char(to_date('88888882345','J'),'Jsp') from dualORA-01854: julian 日期必须介于 1 和 5373484 之间 julian date指的是公元前4712年1月1日起经过的天数.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