Oracle函数有很多种的分类，我们今天要向大家介绍的有Oracle字符函数、Oracle函数中的Oracle数学函数、还有Oracle日期函数以及Oracle转换函数的相关内容的介绍，望你会有所收获。

Oracle字符函数:

lower(char),upper(char),length(char),substr(char,m,n), 
replace(char1,search_string,replace_string),
instr(str,char); 
selectlower(ename)fromemp; 
selectupper(substr(ename,1,1))
||lower(substr(ename,2,length(ename)))fromemp 
selectsubstr(ename,1,3)fromemp; 

select replace(ename,’A’,’我是老鼠’) from emp;

Oracle函数中的Oracle数学函数:

round(n,[m]),trunc(n,[m]),mod(m,n),floor(n),ceil(n);

Oracle日期函数

sysdate,add_months(hire_date,8); 
select*fromemp
wheresysdate>add_months(hiredate,8); 
selectename,trunc(sysdate-hiredate)
"入职天数"fromemp; 
SELECTHIREDATE,ENAMEFROMEMPWHERE
LAST_DAY(HIREDATE)-2=HIREDATE

Oracle转换函数

TO_CHAR 
SQL>SELECTENAME,TO_CHAR(HIREDATE,'YYYY/MM/DDhh24:mi:ss') 
,TO_CHAR(SAL,'L99999.99')FROMEMP; 
SQL>SELECTENAME,HIREDATEFROMEMPWHERETO_CHAR(HIREDATE,' 
YYYY')=1988; 
SQL>SELECTENAME,HIREDATEFROMEMPWHERETO_CHAR(HIREDATE,' 
YYYY-MM')='1988-12'; 

Oracle系统函数:

TERMINAL: 
LANGUAGE: 
DB_NAME: 
NLS_DATE_FORMAT: 
SESSION_USER: 
SELECTSYS_CONTEXT('USERENV','LANGUAGE')FROMDUAL; 
SELECTSYS_CONTEXT('USERENV','SESSION_USER')FROMDUAL;