哪些部门的平均工资比30部门的平均工资要低
哪些部门的平均工资比30部门的平均工资要低select deptno avg(sal) from emp group by deptno where
avg(sal)<(select avg(sal)from emp where deptno=30);

[解决办法]

SQL code

select deptnofrom emp group by deptnohaving avg(sal)<(select avg(sal) from emp where deptno=30);
[解决办法]
SQL code
select deptnofrom emp group by deptnohaving nvl(avg(sal),0)<(select nvl(avg(sal),0) from emp where deptno=30);
[解决办法]
select deptno
from emp group by deptno
having nvl(avg(sal),0)<(select nvl(avg(sal),0) from emp where deptno=30);