各种数据库的连接符

1、oracle、db2、postgresql 使用||用来连接
select ename|| ‘work as a’ ||job as msg from emp where deptno=‘20’;
2、mysql使用concat
select concat(ename,‘work as a’ ,job) as msg from emp where deptno=‘20’;
3、sql server +
select ename +‘work as a’ +job as msg from emp where deptno=‘20’;