1、单行函数—字符函数

字符函数

Upper

SELECT Upper ('abcde') FROM dual ;

SELECT * FROM emp WHEREename=UPPER('smith') ;

Lower

SELECT lower('ABCDE') FROM dual ;

Initcap

函数INITCAP()是将每个单词的第一个字母大写,其它字母变为小写返回.

Select initcap(ename) from emp;

Concat

Select concat(‘a’,’b’)  from dual;

Select ‘a’|| ‘b’from dual;

Substr

Select substr(„abcde‟,length(„abcde‟)-2)from dual;

 Select substr(„abcde‟,-3,3) from dual;

Length

select length('abcde') from dual;

Replace

select replace ('abcdeffddses','s','j') from dual;

Instr

Instr(a,b) 找出字符串b在字符串a中出现的下标位置

Select instr('Hello World','or') from dual;8 indexof

Lpad

lpad('Smith',10,'*') 左侧填充lpad() *****Smith

select lpad('Smith',10,'*')  from dual;

Rpad

rpad('Smith',10,'*') 右侧填充rpad()Smith*****

select rpad('Smith',10,'*')  from dual;

Trim

trim(' Mr Smith     ')过滤首尾空格trim() Mr Smith

select trim('  Mr Smith    ') from dual;