MYSQL包括列w。 0

Question

所以这里的计数是我的查询：

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 

的问题是它只返回行，其中记录大于0的计数有没有一种方法，包括日期，其中计数= 0？

Answer 1

您可以生成自己的日历表中的子查询

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); 

试试看！

CAVEAT：此日历子查询仅在999天之前返回。

可以延伸回到9999天这样

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);