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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 ```