找各个部门领导的最低薪水

# 根据部门编号归类 结果出3个部门
select DEPTNO from emp group by DEPTNO;
# 找经理的名字和工资
select ENAME ,sal from emp where JOB='MANAGER';
# 列出各个部门里领导最低的薪资  3个部门里找到经理的最低工资
select DEPTNO ,min(sal) from emp where JOB='MANAGER' group by DEPTNO;