Question

所以这是我的问题：

SELECT
  COUNT( user_id ) AS `Records` ,
  DATE( FROM_UNIXTIME( `tstamp` ) ) AS `Date`
FROM `user`
WHERE  FROM_UNIXTIME('tstamp') >= '2014-11-00'
GROUP BY DATE( FROM_UNIXTIME( `tstamp` ) )
LIMIT 200

问题是它只返回大于0的记录数的行。是否有办法包括count = 0的日期？

Answer 1

您可以在子查询中生成自己的日历表

SET @start_date = '2014-11-01';
SELECT MyData.dt,IFNULL(MyData.Records,0) Records FROM
(
    SELECT dt FROM
    (SELECT num,(@start_date + INTERVAL num DAY) dt FROM
    (SELECT h*100+t*10+u num FROM
    (SELECT 0 h UNION SELECT 1 UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION
    SELECT 5 UNION SELECT 6 UNION SELECT 7 UNION SELECT 8 UNION SELECT 9) A,
    (SELECT 0 t UNION SELECT 1 UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION
    SELECT 5 UNION SELECT 6 UNION SELECT 7 UNION SELECT 8 UNION SELECT 9) B,
    (SELECT 0 u UNION SELECT 1 UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION
    SELECT 5 UNION SELECT 6 UNION SELECT 7 UNION SELECT 8 UNION SELECT 9) C) AA) AAA
    WHERE dt <= DATE(NOW())
    ORDER BY num
) Calendar LEFT JOIN
(
    SELECT
        COUNT(user_id) AS `Records` ,
        DATE(FROM_UNIXTIME(`tstamp`)) dt
    FROM `user`
    WHERE  FROM_UNIXTIME('tstamp') >= '2014-11-00'
    GROUP BY DATE(FROM_UNIXTIME(`tstamp`))
    LIMIT 200
) MyData USING (dt);

试一试!!!

CAVEAT：这个日历子查询仅在999天前完成。

您可以像这样延长9999天

SET @start_date = '2014-11-01';
SELECT MyData.dt,IFNULL(MyData.Records,0) Records FROM
(
    SELECT dt FROM
    (SELECT num,(@start_date + INTERVAL num DAY) dt FROM
    (SELECT th*1000+h*100+t*10+u num FROM
    (SELECT 0 th UNION SELECT 1 UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION
    SELECT 5 UNION SELECT 6 UNION SELECT 7 UNION SELECT 8 UNION SELECT 9) Z,
    (SELECT 0 h UNION SELECT 1 UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION
    SELECT 5 UNION SELECT 6 UNION SELECT 7 UNION SELECT 8 UNION SELECT 9) A,
    (SELECT 0 t UNION SELECT 1 UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION
    SELECT 5 UNION SELECT 6 UNION SELECT 7 UNION SELECT 8 UNION SELECT 9) B,
    (SELECT 0 u UNION SELECT 1 UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION
    SELECT 5 UNION SELECT 6 UNION SELECT 7 UNION SELECT 8 UNION SELECT 9) C) AA) AAA
    WHERE dt <= DATE(NOW())
    ORDER BY num
) Calendar LEFT JOIN
(
    SELECT
        COUNT(user_id) AS `Records` ,
        DATE(FROM_UNIXTIME(`tstamp`)) dt
    FROM `user`
    WHERE  FROM_UNIXTIME('tstamp') >= '2014-11-00'
    GROUP BY DATE(FROM_UNIXTIME(`tstamp`))
    LIMIT 200
) MyData USING (dt);

MYSQL包含列。数为0

1 个答案: