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SQLite Having 子句


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