28、列出各种工作岗位的最低工资

select job,min(sal) as minSal from emp group by job

29、列出各个部门的经理的最低薪金。

第一步：查询各个部门的所有经理的薪金最低薪水以及部门编号

select deptNo,min(sal) as minSal from emp where job='manager' group by deptNo

第二步：第2步：将第1步查询结果当做临时表t与emp表连接，连接条件：

t.deptno = emp.deptno and emp.sal = t.minsal

select ename,t.deptNo,sal from emp join (select deptNo,min(sal) as minSal from emp where job='manager' group by deptNo) t on t.deptno = emp.deptno and emp.sal = t.minsal

30、列出所有员工的年工资，按年薪从低到高排序

select ename,(sal+ifnull(comm,0))*12 as yearSal from emp order by yearSal asc