mysql update select 从查询结果中更新数据

示例场景

两个表 ordrs, sum_orders， sum_orders 中的count是 orders中相同project_id的count之和；cost同理

一条语句直接更新sum_orders中的count & cost

#orders

 

#sum_orders

 

示例代码

UPDATE sum_orders a
INNER JOIN ( SELECT project_id, sum( count ) AS sum_count, sum( cost ) AS sum_cost FROM orders GROUP BY project_id ) b ON a.project_id = b.project_id 
SET a.count = b.sum_count,
a.cost = b.sum_cost;