📅 最后修改于: 2020-12-29 04:40:48 🧑 作者: Mango
HAVING子句使您可以指定条件，以过滤出哪些组结果出现在结果中。
WHERE子句将条件放在所选列上，而HAVING子句将条件放在GROUP BY子句创建的组上。
以下代码块显示了HAVING子句在查询中的位置。
SELECT
FROM
WHERE
GROUP BY
HAVING
ORDER BY
HAVING子句必须在查询中的GROUP BY子句之后，并且还必须在ORDER BY子句(如果使用)之前。以下代码块具有SELECT语句的语法，包括HAVING子句-
SELECT column1, column2
FROM table1, table2
WHERE [ conditions ]
GROUP BY column1, column2
HAVING [ conditions ]
ORDER BY column1, column2
考虑具有以下记录的CUSTOMERS表。
+----+----------+-----+-----------+----------+
| 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 |
+----+----------+-----+-----------+----------+
以下是一个示例，该示例将显示一个类似的年龄计数(大于或等于2)的记录。
SQL > SELECT ID, NAME, AGE, ADDRESS, SALARY
FROM CUSTOMERS
GROUP BY age
HAVING COUNT(age) >= 2;
这将产生以下结果-
+----+--------+-----+---------+---------+
| ID | NAME | AGE | ADDRESS | SALARY |
+----+--------+-----+---------+---------+
| 2 | Khilan | 25 | Delhi | 1500.00 |
+----+--------+-----+---------+---------+