Select * from emp where not (sal > 3000 or sal < 1500);
寻找那些工资既不大于3000也不小于1500,也即在1500到3000范围的员工,相当于:select * from emp where sal between 1500 and 3000;
注:http://www.cnblogs.com/dongxiaoguang/archive/2013/03/18/2966647.html
Select * from emp where not (sal > 3000 or sal < 1500);
寻找那些工资既不大于3000也不小于1500,也即在1500到3000范围的员工,相当于:select * from emp where sal between 1500 and 3000;
注:http://www.cnblogs.com/dongxiaoguang/archive/2013/03/18/2966647.html