SQLite – HAVING 子句

SQLite – HAVING子句

HAVING使您能够指定过滤条件哪一组结果出现在最终的结果。

WHERE子句的地方条件选定的列, 在有HAVING 子句的地方 就有GROUP BY子句包含的条件组.

语法：

下面是在一个SELECT子句的位置查询:

SELECT

FROM

WHERE

GROUP BY

HAVING

ORDER BY

HAVING 子句必须遵循的GROUP BY子句的查询,还必须先于ORDER BY如果使用它。

下面是SELECT语句的语法,包括有条款:

SELECT column1, column2

FROM table1, table2

WHERE [ conditions ]

GROUP BY column1, column2

HAVING [ conditions ]

ORDER BY column1, column2

例子：

COMPANY table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 

以下是示例,显示记录的名字数小于2:

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 

以下是示例,显示记录数大于2的名字:

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