couter coulmn的累计总和

Question

想要检索以下第一列的累计总和是我的查询：

SELECT COUNT(customer_id) AS entries, DATE(sold_date) as date,
(@cum_sum:=@cum_sum+COUNT(customer_id)) as cumulative 
FROM sold_to 
JOIN (select @cum_sum := 0) B  
WHERE sold_date <= curdate() 
GROUP BY DATE(sold_date) 
LIMIT 0 , 30 

但是，计算总和的结果与第一列相同：

Answer 1

变量和group by混合得不是很好。使用子查询：

SELECT date, entries,
       (@cum_sum := @cum_sum + entries) as cumulative 
FROM (SELECT date(sold_date) as date, count(*) as entries
      FROM sold_to 
      WHERE sold_date <= curdate() 
      GROUP BY date(sold_date)
     ) s CROSS JOIN
     (select @cum_sum := 0) params
ORDER BY date
LIMIT 0 , 30 ;