Sqlite 简明教程

SQLite - HAVING Clause

HAVING 子句允许您指定过滤哪一组结果出现在最终结果中的条件。

HAVING clause enables you to specify conditions that filter which group results appear in the final results.

WHERE 子句对所选的列设置条件，而 HAVING 子句对 GROUP BY 子句创建的组设置条件。

The WHERE clause places conditions on the selected columns, whereas the HAVING clause places conditions on groups created by GROUP BY clause.

Syntax

以下是 HAVING 子句在 SELECT 查询中的位置。

Following is the position of HAVING clause in a SELECT query.

SELECT
FROM
WHERE
GROUP BY
HAVING
ORDER BY

HAVING 子句必须出现在查询中的 GROUP BY 子句之后，如果使用，还必须出现在 ORDER BY 子句之前。以下是包含 HAVING 子句的 SELECT 语句的语法。

HAVING clause must follow GROUP BY clause in a query and must also precede ORDER BY clause if used. Following is the syntax of the SELECT statement, including HAVING clause.

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

Example

考虑具有以下记录的 COMPANY 表。

Consider COMPANY table with the following records.

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

以下是如何显示 name 计数小于 2 的记录的示例。

Following is the example, which will display the record for which the name count is less than 2.

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

这将产生以下结果。

This will produce the following result.

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

以下是如何显示 name 计数大于 2 的记录的示例。

Following is the example, which will display the record for which the name count is greater than 2.

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

这将产生以下结果。

This will produce the following result.

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