HAVING 子句使你能够指定过滤条件，从而控制查询结果中哪些组可以出现在最终结果里面。
WHERE 子句对被选择的列施加条件，而 HAVING 子句则对 GROUP BY 子句所产生的组施加条件。
下面可以看到 HAVING 子句在 SEL ECT 查询中的位置：
SELECT
FROM
WHERE
GROUP BY
HAVING
ORDER BY在 SELECT 查询中，HAVING 子句必须紧随 GROUP BY 子句，并出现在 ORDER BY 子句（如果有的话）之前。带有 HAVING 子句的 SELECT 语句的语法如下所示：
SELECT column1, column2
FROM table1, table2
WHERE [ conditions ]
GROUP BY column1, column2
HAVING [ conditions ]
ORDER BY column1, column2考虑 CUSTOMERS 表，表中的记录如下所示：
+----+----------+-----+-----------+----------+
| ID | NAME | AGE | ADDRESS | SALARY |
+----+----------+-----+-----------+----------+
| 1 | Ramesh | 32 | Ahmedabad | 2000.00 |
| 2 | Khilan | 25 | Delhi | 1500.00 |
| 3 | kaushik | 23 | Kota | 2000.00 |
| 4 | Chaitali | 25 | Mumbai | 6500.00 |
| 5 | Hardik | 27 | Bhopal | 8500.00 |
| 6 | Komal | 22 | MP | 4500.00 |
| 7 | Muffy | 24 | Indore | 10000.00 |
+----+----------+-----+-----------+----------+下面是一个有关 HAVING 子句使用的实例，该实例将会筛选出出现次数大于或等于 2 的所有记录。
SQL > SELECT ID, NAME, AGE, ADDRESS, SALARY
FROM CUSTOMERS
GROUP BY age
HAVING COUNT(age) >= 2;其执行结果如下所示：
+----+----------+-----+---------+---------+
| ID | NAME | AGE | ADDRESS | SALARY |
+----+----------+-----+---------+---------+
| 2 | Khilan | 25 | Delhi | 1500.00 |
| 4 | Chaitali | 25 | Mumbai | 6500.00 |
+----+----------+-----+---------+---------+
原文链接: https://www.yukx.com/moran/article/details/1033.html 优科学习网SQLHAVING子句
