在 WHERE 子句中使用 mysql SUM()

2021-11-20 00:00:00 mysql aggregate-functions having-clause

假设我有这张桌子

id | cash 
1    200
2    301
3    101
4    700

并且我想返回第一行，其中所有先前现金的总和大于某个值:

and I want to return the first row in which the sum of all the previous cash is greater than a certain value:

例如，如果我想返回所有先前现金总和大于 500 的第一行，则应返回到第 3 行

So for instance, if I want to return the first row in which the sum of all the previous cash is greater than 500, is should return to row 3

如何使用 mysql 语句执行此操作?

How do I do this using mysql statement?

使用 WHERE SUM(cash) >500不起作用

推荐答案

你只能在 HAVING 子句中使用聚合进行比较:

You can only use aggregates for comparison in the HAVING clause:

GROUP BY ...
  HAVING SUM(cash) > 500

HAVING 子句要求您定义一个 GROUP BY 子句.

The HAVING clause requires you to define a GROUP BY clause.

要获取所有先前现金总和大于某个值的第一行，请使用:

To get the first row where the sum of all the previous cash is greater than a certain value, use:

SELECT y.id, y.cash
  FROM (SELECT t.id,
               t.cash,
               (SELECT SUM(x.cash)
                  FROM TABLE x
                 WHERE x.id <= t.id) AS running_total
         FROM TABLE t
     ORDER BY t.id) y
 WHERE y.running_total > 500
ORDER BY y.id
   LIMIT 1

因为聚合函数出现在子查询中，所以可以在 WHERE 子句中引用它的列别名.

Because the aggregate function occurs in a subquery, the column alias for it can be referenced in the WHERE clause.

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