mysql - 按值之和限制查询

Question

我有一个 mysql 表，transactions，包含字段 id、transactionType、quantity、price 等。我想通过一列的累计总和来限制记录。所以我想取出所有的交易，直到累计数量达到我的变量(这里<=50)。

我做错了什么？

SET @qsum := 0; 
SELECT * 
FROM (
  SELECT *, (@qsum := @qsum + quantity) AS cumulative_quantity 
  FROM transactions ORDER BY id DESC
) transactions 
WHERE 
transactionType = 'buy'
AND typeID = 10
AND cumulative_quantity <= 50

Answer 1

试试这个

SET @qsum := 0; 
SELECT * 
FROM (
  SELECT *, (@qsum := @qsum + quantity) AS cumulative_quantity 
  FROM transactions
  WHERE transactionType = 'buy'
   AND typeID = 10
   AND cumulative_quantity <= 50
  ORDER BY id DESC
) transaction