Oracle基础学习(一)常用函数

2017-01-12 19:05:38来源:cnblogs.com作者:大蒲扇人点击

1.绝对值:abs()

select abs(-2) value from dual;

2.取整函数(大):ceil()

select ceil(-2.001) value from dual;(-2)

3.取整函数(小):floor()

select floor(-2.001) value from dual;(-3)

4.取整函数(截取):trunc()

select trunc(-2.001) value from dual; (-2)

5.四舍五入:round()

select round(1.234564) value from dual;(1.2346)

6.取平方:Power(m,n)

select power(4,2) value from dual;(16)

7.取平方根:SQRT()

select sqrt(16) value from dual;(4)

8.取随机数:dbms_random(minvalue,maxvalue)

select sys.dbms.random.value(0,1) value from dual;

9.取符号:Sign()

select sign(-3) value from dual;(-)

10,取集合的最大值:greatest(value)

select greatest(-1,3,5,7,9) value from dual;(9)

11.取集合的最小值:least(value)

select least(-1,3,5,7,9) value from dual;(-1)

12.处理Null值:nvl(空值,代替值)

select nvl(null,10) value from dual;(10)

13.求字符序号:ascii()

select ascii(a) value from dual;

14.求序号字符:chr()

select chr(97) value from dual;

15.链接:concat()

select concat("11","22") value from dual;(1122)

16.获取系统时间:sysdate()

select sysdate value from dual;

17.求日期

select trunc(sysdate) from dual;

18.求时间

select to_char(sysdate,"hh24:mm:ss") from dual;

19.首字母大写:InitCAP()

select INITCAP(abc def ghi) value from dual;tbw(Abc Def Ghi)

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