Question

新秀需要一些帮助。有人可以提供一个查询来轻松计算，然后按月匹配两个条件的记录制表，以避免使用像这样笨拙的重复代码......

SELECT 
SUM( CASE  
    WHEN extract( YEAR FROM  `date` ) =  "2017" 
    AND extract( MONTH FROM  `date` ) =  "07"
    AND  `conditionA` =  "A" 
    AND  `conditionB` =  "B" 
    THEN 1 else 0 END ) 
AS 2017_07

SUM( CASE  
    WHEN extract( YEAR FROM  `date` ) =  "2017" 
    AND extract( MONTH FROM  `date` ) =  "08"
    AND  `conditionA` =  "A" 
    AND  `conditionB` =  "B" 
    THEN 1 else 0 END ) 
AS 2017_08

SUM( CASE  
    WHEN extract( YEAR FROM  `date` ) =  "2017" 
    AND extract( MONTH FROM  `date` ) =  "09"
    AND  `conditionA` =  "A" 
    AND  `conditionB` =  "B" 
    THEN 1 else 0 END ) 
AS 2017_09

FROM  `datatable`

Answer 1

将数据放入行而不是列：

SELECT extract( YEAR FROM  `date` ) as yyyy, extract( MONTH FROM  `date` ) as mm,
       COUNT(*)
FROM datatable
WHERE `conditionA` =  'A' AND  `conditionB` =  'B'
GROUP BY extract( YEAR FROM  `date` ), extract( MONTH FROM  `date` )
ORDER BY yyyy, mm ;

伯爵＆amp;按月列出匹配记录

1 个答案: