• 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
    

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  • 原文地址:https://www.cnblogs.com/orangebook/p/3501708.html
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