Oracle PLSQL之HAVING后面的条件可由聚合函数构成，也可由GROUP BY后的字段构成

SQL> select * from dept;

DEPTNO DNAME          LOC
------ -------------- -------------
10 ACCOUNTING     NEW YORK
20 RESEARCH       DALLAS
30 SALES          CHICAGO
40 OPERATIONS     BOSTON
50 name1          loc1
51 name1          name1
52 loc1           loc1

7 rows selected

SQL> SELECT loc FROM dept GROUP BY loc HAVING count(deptno)>1;

LOC
-------------
loc1

SQL> SELECT loc FROM dept GROUP BY loc HAVING deptno>30;

SELECT loc FROM dept GROUP BY loc HAVING deptno>30

ORA-00979: not a GROUP BY expression

SQL> SELECT loc FROM dept GROUP BY loc,deptno HAVING deptno>30;

LOC
-------------
BOSTON
loc1
loc1
name1

SQL> SELECT loc,deptno FROM dept GROUP BY loc,deptno HAVING deptno>30;

LOC           DEPTNO
------------- ------
BOSTON            40
loc1              50
loc1              52
name1             51

SQL>