MySQL Mysql to select month-wise record even if data not exist

다음과 같이 사용자 테이블에 월별 레코드를 가져 오는 쿼리를 작성했습니다.

SELECT COUNT( `userID` ) AS total, DATE_FORMAT( `userRegistredDate` , '%b' ) AS
MONTH , YEAR( `userRegistredDate` ) AS year
FROM `users`
GROUP BY DATE_FORMAT( FROM_UNIXTIME( `userRegistredDate` , '%b' ) )

산출:

total      MONTH    year
---------------------------
3           May     2013
2           Jul     2013
--------------------------

예상 출력 :

total      MONTH    year
---------------------------
 0          Jan     2013
 0          Feb     2013
 0          Mar     2013
 0          Apr     2013
 3          May     2013
 0          Jun     2013 
 2          Jul     2013
--------------------------

데이터가 없어도 기록을 보여줘야합니다. 어떻게하나요?

 

해결 방법

 

다른 방법에 대해 테스트하지 않았기 때문에 효율성에 대해 많이 말하지 않을 것이지만 임시 테이블이 없으면 이것은 공정한 방법으로 보입니다.

   SELECT COUNT(u.userID) AS total, m.month
     FROM (
           SELECT 'Jan' AS MONTH
           UNION SELECT 'Feb' AS MONTH
           UNION SELECT 'Mar' AS MONTH
           UNION SELECT 'Apr' AS MONTH
           UNION SELECT 'May' AS MONTH
           UNION SELECT 'Jun' AS MONTH
           UNION SELECT 'Jul' AS MONTH
           UNION SELECT 'Aug' AS MONTH
           UNION SELECT 'Sep' AS MONTH
           UNION SELECT 'Oct' AS MONTH
           UNION SELECT 'Nov' AS MONTH
           UNION SELECT 'Dec' AS MONTH
          ) AS m
LEFT JOIN users u 
ON MONTH(STR_TO_DATE(CONCAT(m.month, ' 2013'),'%M %Y')) = MONTH(u.userRegistredDate)
   AND YEAR(u.userRegistredDate) = '2013'
GROUP BY m.month
ORDER BY 1+1;

날짜 형식을 기반으로 유니온을 만들면 작업을 줄이고 쿼리에 대한로드를 줄일 수도 있습니다.

   SELECT COUNT(u.userID) AS total, DATE_FORMAT(merge_date,'%b') AS month, YEAR(m.merge_date) AS year
     FROM (
           SELECT '2013-01-01' AS merge_date
           UNION SELECT '2013-02-01' AS merge_date
           UNION SELECT '2013-03-01' AS merge_date
           UNION SELECT '2013-04-01' AS merge_date
           UNION SELECT '2013-05-01' AS merge_date
           UNION SELECT '2013-06-01' AS merge_date
           UNION SELECT '2013-07-01' AS merge_date
           UNION SELECT '2013-08-01' AS merge_date
           UNION SELECT '2013-09-01' AS merge_date
           UNION SELECT '2013-10-01' AS merge_date
           UNION SELECT '2013-11-01' AS merge_date
           UNION SELECT '2013-12-01' AS merge_date
          ) AS m
LEFT JOIN users u 
       ON MONTH(m.merge_date) = MONTH(u.userRegistredDate)
          AND YEAR(m.merge_date) = YEAR(u.userRegistredDate)
GROUP BY m.merge_date
ORDER BY 1+1;

 

참조 페이지 https://stackoverflow.com/questions/17916322