HAVING 子句允许指定条件来过滤将出现在最终结果中的分组结果。

WHERE 子句在所选列上设置条件,而 HAVING 子句则在由 GROUP BY 子句创建的分组上设置条件。

语法

下面是 HAVING 子句在 SELECT 查询中的位置:

SELECT
FROM
WHERE
GROUP BY
HAVING
ORDER BY

在一个查询中,HAVING 子句必须放在 GROUP BY 子句之后,必须放在 ORDER BY 子句之前。下面是包含 HAVING 子句的 SELECT 语句的语法:

SELECT column1, column2
FROM table1, table2
WHERE [ conditions ]
GROUP BY column1, column2
HAVING [ conditions ]
ORDER BY column1, column2

实例

假设 COMPANY 表有以下记录:

ID NAME AGE ADDRESS SALARY
---------- ---------- ---------- ---------- ----------
1 Paul 32 California 20000.0
2 Allen 25 Texas 15000.0
3 Teddy 23 Norway 20000.0
4 Mark 25 Rich-Mond 65000.0
5 David 27 Texas 85000.0
6 Kim 22 South-Hall 45000.0
7 James 24 Houston 10000.0
8 Paul 24 Houston 20000.0
9 James 44 Norway 5000.0
10 James 45 Texas 5000.0

下面是一个实例,它将显示名称计数小于 2 的所有记录:

sqlite > SELECT * FROM COMPANY GROUP BY name HAVING count(name) < 2;

这将产生以下结果:

ID NAME AGE ADDRESS SALARY
---------- ---------- ---------- ---------- ----------
2 Allen 25 Texas 15000
5 David 27 Texas 85000
6 Kim 22 South-Hall 45000
4 Mark 25 Rich-Mond 65000
3 Teddy 23 Norway 20000

下面是一个实例,它将显示名称计数大于 2 的所有记录:

sqlite > SELECT * FROM COMPANY GROUP BY name HAVING count(name) > 2;

这将产生以下结果:

ID NAME AGE ADDRESS SALARY
---------- ---------- ---------- ---------- ----------
10 James 45 Texas 5000