1. Absolute value: abs()
select abs(-2) value from dual;
2. Rounding function (large): ceil()
select ceil(-2.001) value from dual;(-2)
3. Rounding function (small): floor()
select floor(-2.001) value from dual;(-3)
4. Rounding function (intercept): trunc()
select trunc(-2.001) value from dual; (-2)
5. Rounding: round()
select round(1.234564) value from dual;(1.2346)
6. Take the square: Power (m, n)
select power(4,2) value from dual;(16)
7. Take the square root: SQRT()
select sqrt(16) value from dual;(4)
8. Take a random number: dbms_random(minvalue,maxvalue)
select sys.dbms.random.value(0,1) value from dual;
9. Take the sign: Sign()
select sign(-3) value from dual;(-)
10, take the maximum value of the set: greater(value)
select greatest(-1,3,5,7,9) value from dual;(9)
11. Take the minimum value of the set: least(value)
select least(-1,3,5,7,9) value from dual;(-1)
12. Handling Null values: nvl (null value, instead of value)
select nvl(null,10) value from dual;(10)
13. Find the character number: ascii()
select ascii(a) value from dual;
14. Find the serial number character: chr()
select chr(97) value from dual;
15. Link: concat()
select concat("11","22") value from dual;(1122)
16. Get system time: sysdate()
select sysdate value from dual;
17. Ask for the date
select trunc(sysdate) from dual;
18. Ask for time
select to_char(sysdate,"hh24:mm:ss") from dual;
19. Capitalize the first letter: InitCAP()
select INITCAP(abc def ghi) value from dual;(Abc Def Ghi)