Question

我需要获取devicePoint，osPoint，browserPoint的总和，这是使用SELECT中的case语句填充的。这是我的代码

SELECT *,
    CASE
        WHEN device='Default' THEN 1
        ELSE 5
    END AS devicePoint,
    CASE
        WHEN operating_system='Default' THEN 1
        ELSE 3
    END AS osPoint,
    CASE
        WHEN browser='Default' THEN 1
        ELSE 2
    END AS browserPoint,
    (devicePoint + osPoint + browserPoint) as 'Total'
FROM mytable
WHERE 
 (
    (device = 'Desktop' AND operating_system='Ios' AND browser='Firefox')
    OR
    (device = 'Desktop' AND operating_system='Ios' AND browser='Default')
    OR 
    (device = 'Desktop' AND operating_system='Default' AND browser='Firefox')
    OR 
    (device = 'Desktop' AND operating_system='Default' AND browser='Default')
    OR 
    (device = 'Default' AND operating_system='Ios' AND browser='Default')
    OR 
    (device = 'Default' AND operating_system='Default' AND browser='Firefox')
    OR 
    (device = 'Default' AND operating_system='Default' AND browser='Default')
)

Answer 1

使用子查询：

SELECT
    devicePoint,
    osPoint,
    browserPoint,
    (devicePoint + osPoint + browserPoint) AS Total
FROM
(
    SELECT *,
        CASE WHEN device = 'Default' THEN 1 ELSE 5 END AS devicePoint,
        CASE WHEN operating_system = 'Default' THEN 1 ELSE 3 END AS osPoint,
        CASE WHEN browser = 'Default' THEN 1 ELSE 2 END AS browserPoint
    FROM mytable
    WHERE 
        (device = 'Desktop' AND operating_system='Ios' AND browser='Firefox') OR
        (device = 'Desktop' AND operating_system='Ios' AND browser='Default') OR
        (device = 'Desktop' AND operating_system='Default' AND browser='Firefox') OR
        (device = 'Desktop' AND operating_system='Default' AND browser='Default') OR
        (device = 'Default' AND operating_system='Ios' AND browser='Default') OR
        (device = 'Default' AND operating_system='Default' AND browser='Firefox') OR
        (device = 'Default' AND operating_system='Default' AND browser='Default')
) t;

不可能在定义它们的同一SELECT中引用您的三个别名。但是，如果您使用上面的子查询方法，它们将可用。

Answer 2

我提供了一个答案，因为您可以简化where子句，因为MySQL支持元组。逻辑看起来像这样：

select t.*,
       (devicePoint + osPoint + browserPoint) as 'Total'
from (select (case when device = 'Default' then 1 else 5 end) as devicePoint,
             (case when operating_system = 'Default' then 1 else 3 end) as osPoint,
             (case when browser = 'Default' then 1 else 2 end) as browserPoint        
      from mytable t
      where (device, operating_system, browser) in
                ( ('Desktop', 'Ios', 'Firefox'),
                  ('Desktop', 'Ios', 'Default'),
                  . . .
                )
     ) t;

Answer 3

这是最简单的 WHERE 子句。

SELECT *,
    CASE
        WHEN device='Default' THEN 1
        ELSE 5
    END AS devicePoint,
    CASE
        WHEN operating_system='Default' THEN 1
        ELSE 3
    END AS osPoint,
    CASE
        WHEN browser='Default' THEN 1
        ELSE 2
    END AS browserPoint,
    (devicePoint + osPoint + browserPoint) as 'Total'
FROM mytable
WHERE 
 (device IN ('Desktop','Default') AND operating_system IN ('Ios','Default') AND browser IN ('Firefox','Default'))

使用SQL中的case语句填充的三列之和

3 个答案: