如何检索单个 MySQL 表中包含空行的最近 7 天的交易？

检索最近 7 天的交易并在 MySQL 单表中包含空行

解决提取最近 7 天交易的挑战并从 MySQL 数据库捕获空行，我们将遍历以下内容方法：

1. 生成日期范围：
   我们首先使用以下查询创建过去 7 天的日期列表：

   select DATE_FORMAT(a.Date,'%Y-%m-%d') as purchase_date,
   '0' as  amount
   from (
      select curdate() - INTERVAL (a.a + (10 * b.a) + (100 * c.a)) DAY as Date
      from (select 0 as a union all select 1 union all select 2 union all select 3 union all select 4 union all select 5 union all select 6 union all select 7 union all select 8 union all select 9) as a
      cross join (select 0 as a union all select 1 union all select 2 union all select 3 union all select 4 union all select 5 union all select 6 union all select 7 union all select 8 union all select 9) as b
      cross join (select 0 as a union all select 1 union all select 2 union all select 3 union all select 4 union all select 5 union all select 6 union all select 7 union all select 8 union all select 9) as c
   ) a
   where a.Date BETWEEN NOW() - INTERVAL 7 DAY AND NOW()

2. 加入交易表：
   接下来，我们将生成的日期列表与交易表连接起来，获取相应的销售额（如果有）：

   SELECT t1.purchase_date,
   coalesce(SUM(t1.amount+t2.amount), 0) AS amount
   from

   (
     select DATE_FORMAT(a.Date,'%Y-%m-%d') as purchase_date,
     '0' as  amount
     from (
        select curdate() - INTERVAL (a.a + (10 * b.a) + (100 * c.a)) DAY as Date
        from (select 0 as a union all select 1 union all select 2 union all select 3 union all select 4 union all select 5 union all select 6 union all select 7 union all select 8 union all select 9) as a
        cross join (select 0 as a union all select 1 union all select 2 union all select 3 union all select 4 union all select 5 union all select 6 union all select 7 union all select 8 union all select 9) as b
        cross join (select 0 as a union all select 1 union all select 2 union all select 3 union all select 4 union all select 5 union all select 6 union all select 7 union all select 8 union all select 9) as c
     ) a
     where a.Date BETWEEN NOW() - INTERVAL 7 DAY AND NOW()
   )t1
   left join

   (
     SELECT DATE_FORMAT(purchase_date, '%Y-%m-%d') as purchase_date,
     coalesce(SUM(amount), 0) AS amount
     FROM transactions
     WHERE purchase_date BETWEEN NOW() - INTERVAL 7 DAY AND NOW()
     AND vendor_id = 0
     GROUP BY purchase_date
   )t2
   on t2.purchase_date = t1.purchase_date
   group by t1.purchase_date
   order by t1.purchase_date desc

完整查询：

select 
t1.purchase_date,
coalesce(SUM(t1.amount+t2.amount), 0) AS amount
from
(
  select DATE_FORMAT(a.Date,'%Y-%m-%d') as purchase_date,
  '0' as  amount
  from (
    select curdate() - INTERVAL (a.a + (10 * b.a) + (100 * c.a)) DAY as Date
    from (select 0 as a union all select 1 union all select 2 union all select 3 union all select 4 union all select 5 union all select 6 union all select 7 union all select 8 union all select 9) as a
    cross join (select 0 as a union all select 1 union all select 2 union all select 3 union all select 4 union all select 5 union all select 6 union all select 7 union all select 8 union all select 9) as b
    cross join (select 0 as a union all select 1 union all select 2 union all select 3 union all select 4 union all select 5 union all select 6 union all select 7 union all select 8 union all select 9) as c
  ) a
  where a.Date BETWEEN NOW() - INTERVAL 7 DAY AND NOW()
)t1
left join
(
  SELECT DATE_FORMAT(purchase_date, '%Y-%m-%d') as purchase_date,
  coalesce(SUM(amount), 0) AS amount
  FROM transactions
  WHERE purchase_date BETWEEN NOW() - INTERVAL 7 DAY AND NOW()
  AND vendor_id = 0
  GROUP BY purchase_date
)t2
on t2.purchase_date = t1.purchase_date
group by t1.purchase_date
order by t1.purchase_date desc

利用此综合查询，我们可以提取过去 7 天每一天的总销售额，有效地包括没有交易的日子的空行。

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