1.连接函数CONCAT
SQL> select concat(‘Hello‘,‘World‘) from dual; CONCAT(‘HE ---------- HelloWorld
2.截取字符串长度SUBSTR
SQL> select substr(‘HelloWorld‘,1,5) from dual; SUBST ----- Hello
3.长度LENGTH
SQL> select length(‘HelloWorld‘) from dual; LENGTH(‘HELLOWORLD‘) -------------------- 10
4.某个字符第一次出现的位置数INSTR
SQL> select instr(‘HelloWorld‘,‘W‘) from dual; INSTR(‘HELLOWORLD‘,‘W‘) ----------------------- 6
5.左补齐和右补齐LPAD,RPAD
SQL> select lpad(salary,10,‘#‘) from employees where employee_id=206; LPAD(SALARY,10,‘#‘) ---------------------------------------- ######8300 SQL> select rpad(salary,10,‘#‘) from employees where employee_id=206; RPAD(SALARY,10,‘#‘) ---------------------------------------- 8300######
6.删除字符串首尾的空白TRIM
SQL> select trim(‘H‘ from ‘HelloWorld‘) from dual; TRIM(‘H‘F --------- elloWorld
原文：http://www.cnblogs.com/tomatoes-/p/6065201.html