1. and where having different points
(1) back where the function can write packet, the packet may be used and later having a function.
(2) having only a group by group statistics statement.
2. Case practical operation
(1) find the average wage for each department
hive (default)> select deptno, avg(sal) from emp group by deptno;
(2) The average salary for each department seeking more than 2,000 department
hive (default)> select deptno, avg(sal) avg_sal from emp group by deptno having avg_sal > 2000;