Oracle使用||与concat实现字段或字符串拼接

SQL> select first_name||'''s SALARY is : '||salary as "name,sal" from employees e where e.employee_id=100;


name,sal
----------------------------------------------------------------------------
Steven's SALARY is : 24000


SQL> select concat(first_name||' ',salary) as "name,sal" from employees e where e.employee_id=100;


name,sal
-------------------------------------------------------------
Steven 24000


SQL> select concat(first_name||'''s salary is ',salary) as "name,sal" from employees e where e.employee_id=100;


name,sal
-------------------------------------------------------------------------
Steven's salary is 24000