如何获得数据时，我有两个表SQL组的多个表的入口

Question

我有两个表

点击

1. 2.骑

click Table
id | time

ride Table
id |时间戳

我想从两个表中获取数据组by group by EXTRACT(DAY from ride.timestamp)但我只得到数据，如果我有条目在两个表的同一天，但我想要的数据，无论是否表没有数据。我不知道如果外连接是一个答案，但mysql不支持外连接

我的当前查询，只有在两个表中都有条目时才能获得数据

COUNT(distinct ride.id) AS ride_ads, 
COUNT(distinct clicks.id) AS clicks
FROM ride INNER JOIN clicks ON EXTRACT(DAY FROM ride.timestamp)=EXTRACT(DAY FROM clicks.time)
GROUP BY EXTRACT(DAY FROM ride.timestamp), EXTRACT(DAY FROM clicks.time)```

Answer 1

SELECT 
DATE(ride.timestamp) AS Day,
COUNT(DISTINCT ride.id) AS ride_ads,
COUNT(DISTINCT clicks.id) AS clicks
FROM
ride
LEFT JOIN
clicks ON DATE(ride.timestamp) = DATE(clicks.time)
WHERE
DATE(ride.timestamp) > NOW() - INTERVAL 15 DAY
GROUP BY Day 
UNION SELECT 
DATE(clicks.time) AS Day, #selecting date from second table since I might have record in this table and I am using group by Day 
COUNT(DISTINCT ride.id) AS ride_ads,
COUNT(DISTINCT clicks.id) AS clicks
FROM
ride
RIGHT JOIN
clicks ON DATE(ride.timestamp) = DATE(clicks.time)
WHERE
DATE(clicks.time) > NOW() - INTERVAL 15 DAY
GROUP BY Day
ORDER BY Day