mysql 查詢近7天數據，缺失補0

相信不少人的項目都有這種需求，就是查詢近7天的記錄，可是這7天總有那麼幾天是沒數據的，因此缺失的只能補 0 

下面的代碼不知道能不能看懂，我簡單的說一下思路

1）先查詢紅色字體的近7天，再轉換成日期

2）個人字段使用的是時間戳的方式去保存，只能是先數據庫字段先轉日期

2.1）先查詢本身想要的數據，用天天分組，計算好總數後

2.2）時間戳字段先轉日期

2.3）用 ifnull 函數判斷，缺失就補 0 

而後~~~~而後就大功告成啦

select temp.days, ifnull(walletTemp.money, 0) as money from (
SELECT curdate() as days
union all
SELECT date_sub(curdate(), interval 1 day) as days
union all
SELECT date_sub(curdate(), interval 2 day) as days
union all
SELECT date_sub(curdate(), interval 3 day) as days
union all
SELECT date_sub(curdate(), interval 4 day) as days
union all
SELECT date_sub(curdate(), interval 5 day) as days
union all
SELECT date_sub(curdate(), interval 6 day) as days ) as temp
left join
(select date(FROM_UNIXTIME(createAt, '%Y%m%d')) as datetime, sum(money) as money
from wb_car_wallet where driverId = 'e472e99da1be45918c82d92753382ac3'
and type = 0 or type = 1
group by from_unixtime(createAt, '%Y-%m-%d')
order by createAt) as walletTemp on temp.days = walletTemp.datetime