Question

我试图找出上个月进行销售但本月未进行销售的卖家数量。

我有一个有效的查询，但我认为它没有效率，而且我还没有弄清楚如何在所有月份都这样做。

SELECT count(distinct user_id) as users
FROM transactions
WHERE MONTH(date) = 12
AND YEAR(date) = 2015
AND transactions.status = 'COMPLETED'
AND transactions.amount > 0
AND transactions.user_id NOT IN 
(
    SELECT distinct user_id
    FROM transactions
    WHERE MONTH(date) = 1
    AND YEAR(date) = 2016
    AND transactions.status = 'COMPLETED'
    AND transactions.amount > 0
)

表的结构是：

+---------+------------+-------------+--------+
| user_id |    date    |   status    | amount |
+---------+------------+-------------+--------+
|       1 | 2016-01-01 | 'COMPLETED' | 1.00   |
|       2 | 2015-12-01 | 'COMPLETED' | 1.00   |
|       3 | 2015-12-01 | 'COMPLETED' | 2.00   |
|       1 | 2015-12-01 | 'COMPLETED' | 3.00   |
+---------+------------+-------------+--------+

因此，在这种情况下，ID为2和3的用户本月没有进行销售。

Answer 1

使用条件聚合：

SELECT count(*) as users
FROM
 (
    SELECT user_id
    FROM transactions
                       -- 1st of previous month
    WHERE date BETWEEN SUBDATE(SUBDATE(CURRENT_DATE, DAYOFMONTH(CURRENT_DATE)-1), interval 1 month) 
                       -- end of current month
                   AND LAST_DAY(CURRENT_DATE)
    AND transactions.status = 'COMPLETED'
    AND transactions.amount > 0
    GROUP BY user_id
           -- any row from previous month
    HAVING MAX(CASE WHEN date < SUBDATE(CURRENT_DATE, DAYOFMONTH(CURRENT_DATE)-1)
                    THEN date 
               END) IS NOT NULL
           -- no row in current month
       AND MAX(CASE WHEN date >= SUBDATE(CURRENT_DATE, DAYOFMONTH(CURRENT_DATE)-1)
                    THEN date 
               END) IS NULL           
 ) AS dt

SUBDATE(CURRENT_DATE, DAYOFMONTH(CURRENT_DATE)-1) =当月的第一天

SUBDATE(first day of current month, interval 1 month) =上个月的第一天

LAST_DAY(CURRENT_DATE) =当月结束

Answer 2

如果您想要对其进行生成，可以使用curdate()获取当前月份，并使用DATE_SUB(curdate(), INTERVAL 1 MONTH)获取上个月（您需要为1月/ 12月执行一些if子句）：< / p>

SELECT count(distinct user_id) as users
FROM transactions
WHERE MONTH(date) = MONTH(DATE_SUB(curdate(), INTERVAL 1 MONTH))
AND transactions.status = 'COMPLETED'
AND transactions.amount > 0
AND transactions.user_id NOT IN 
(
    SELECT distinct user_id
    FROM transactions
    WHERE MONTH(date) = MONTH(curdate())
    AND transactions.status = 'COMPLETED'
    AND transactions.amount > 0
)

就效率而言，我没有看到这个问题

Answer 3

以下应该非常有效。为了使其更加如此，您需要提供表定义和EXPLAIN。

SELECT COUNT(DISTINCT user_id) users
  FROM transactions t
  LEFT 
  JOIN transactions x
    ON x.user_id = t.user_id
   AND x.date BETWEEN '2016-01-01' AND '2016-01-31'
   AND x.status = 'COMPLETED'
   AND x.amount > 0
 WHERE t.date BETWEEN '2015-12-01' AND '2015-12-31'
   AND t.status = 'COMPLETED'
   AND t.amount > 0
   AND x.user_id IS NULL;

Answer 4

只是一些思考的输入：
您可以每月创建用户ID的汇总列表，代表该月的所有唯一买家。在您的应用程序中，您只需要减去相关的两个月，以获得仅在两个月中的一个月内进行销售的所有用户ID。
请参阅下面的查询和后处理示例。

为了使您的查询更有效，我建议[status, amount]上的表事务至少有一个2列索引。但是，为了防止查询必须在实际表中查找数据，您甚至可以创建一个4列索引[status, amount, date, user_id]，这将进一步提高查询的性能。

Postgres （v9.0 +，已测试）

SELECT   (DATE_PART('year', t.date) || '-' || DATE_PART('month', t.date)) AS d,
         STRING_AGG( DISTINCT t.user_id::TEXT, ',' ) AS buyers
FROM     transactions t
WHERE    t.status = 'COMPLETED'
AND      t.amount > 0
GROUP BY DATE_PART('year', t.date),
         DATE_PART('month', t.date)
ORDER BY DATE_PART('year', t.date),
         DATE_PART('month', t.date)
;

MySQL （未经测试）

SELECT   (YEAR(t.date) || '-' || MONTH(t.date)) AS d,
         GROUP_CONCAT( DISTINCT t.user_id ) AS buyers
FROM     transactions t
WHERE    t.status = 'COMPLETED'
AND      t.amount > 0
GROUP BY YEAR(t.date), MONTH(t.date)
ORDER BY YEAR(t.date), MONTH(t.date)
;

Ruby （后处理示例）

db_result                   = ActiveRecord::Base.connection_pool.with_connection { |con| con.execute( db_query ) }
unique_buyers               = db_result.map{|e|[e['d'],e['buyers'].split(',')]}.to_h

buyers_dec15_but_not_jan16  = unique_buyers['2015-12'] - unique_buyers['2016-1']
buyers_nov15_but_not_dec16  = unique_buyers['2015-11']||[] - unique_buyers['2015-12']
...(and so on)...

SQL Query查找本月未发生的行

4 个答案: