CHARACTER：
Function--------------------------------------------Result
concat('Hello','World')--------------------------------------'HelloWorld'
substr('HelloWorld',1,5)------------------------------------'Hello'
length('HelloWorld')-----------------------------------------10
instr('HelloWorld','W')---------------------------------------6
lpad(salary,10,'*')--------------------------------------------*****24000
rpad(salary,10,'*')--------------------------------------------24000*****
trim('H' from 'HelloWorld')---------------------------------elloWorld
NUMBER：
Function--------------------------------------------Result
round(45.926,2)---------------------------------------------45.93
trunc(45.926,2)----------------------------------------------45.92
mod(1600,300)----------------------------------------------100
round(45.926,0)---------------------------------------------46
round(45.926,-1)--------------------------------------------50
DATE：
Function--------------------------------------------Result
months_between('01-sep-95','11-jan-94')----------19.6774194
add_months('11-JAN-94',6)------------------------------'11-JUL-94'
next_day('01-SEP-95','FRIDAY')------------------------'08-SEP-95'
last_day('01-FEB-95')---------------------------------------'28-FEB-95'