Mysql 日期范围按行动态更改

我需要为查询结果的每一行指定日期范围，例如：

    select 
    DATE_FORMAT(date_purchase, '%Y-%m')as Year_month,
    count(*) as Count
    from tickets 
    where date_purchase BETWEEN '2019-01-01' AND '2019-03-31'
group by Year_month

此查询将给出该结果：

Year_month | Count
2019-01    | 134
2019-02    | 154
2019-03    | 123

但与一年前的计数相比，我需要再增加一列，预期结果如下：

Year_month | Count | Count_One_Year_Ago_Per_Month
2019-01    | 134   | (count(*) between 2018-01 and 2019-01)
2019-02    | 154   | (count(*) between 2018-02 and 2019-02)
2019-03    | 123   | (count(*) between 2018-03 and 2019-03)

最好的方法是什么

---

编辑：我的Mysql版本是5.7

如果您有所有月份的数据，最简单的方法是使用lag：

编辑：

您还可以使用条件聚合：

select month(date_purchase),
       sum(year(date_purchase) = 2018) as cnt_2018,
       sum(year(date_purchase) = 2019) as cnt_2019
from tickets t
where date_purchase >= '2018-01-01' and
      date_purchase < '2019-04-01' and
      month(date_purchase) in (1, 2, 3)
group by month(date_purchase);

我认为，如果您想要完整的年数，可能需要一个相关子查询：

select ym.*,
       (select count(*)
        from tickets t2
        where date_format(t2.date_purchase, '%Y-%m') < ym.year_month and
              date_format(t2.date_purchase + interval 1 year, '%Y-%m') >= ym.year_month
       ) as prev_cumulative_year
from (select date_format(sa.date_purchase, '%Y-%m') as Year_month,
             count(*) as Count
      from tickets t
      group by Year_month
     ) ym

---

你可以检查这个脚本-

您可以使用一些示例数据来检查

SELECT 
A.date_purchase,
MAX(c_count) Current_month_count,
COUNT(*) last_year_count
FROM 
(
    SELECT 
    DATE_FORMAT(date_purchase, '%Y-%m') AS `date_purchase`,
    COUNT(*) c_count 
    FROM tickets
    GROUP BY DATE_FORMAT(date_purchase, '%Y-%m')
)A
INNER JOIN tickets B 
    ON  A.date_purchase 
    BETWEEN

        DATE_FORMAT(B.date_purchase, '%Y-%m')
        AND
        DATE_FORMAT(B.date_purchase + interval 12 month, '%Y-%m')

GROUP BY A.date_purchase

---

我忘记提到的一个细节是，我的MYSQL版本是5.7.26，所以我不能使用滞后功能：/谢谢，但是编辑给了我每年每个月的计数，而不是一年的全部数据，例如：2018-01和2019-01之间的计数。

SELECT 
A.date_purchase,
MAX(c_count) Current_month_count,
COUNT(*) last_year_count
FROM 
(
    SELECT 
    DATE_FORMAT(date_purchase, '%Y-%m') AS `date_purchase`,
    COUNT(*) c_count 
    FROM tickets
    GROUP BY DATE_FORMAT(date_purchase, '%Y-%m')
)A
INNER JOIN tickets B 
    ON  A.date_purchase 
    BETWEEN

        DATE_FORMAT(B.date_purchase, '%Y-%m')
        AND
        DATE_FORMAT(B.date_purchase + interval 12 month, '%Y-%m')

GROUP BY A.date_purchase