我正在尝试为每个客户选择最新的工作订单。我使用了 ORDER BY 和 GROUP BY，但返回的结果不是最新的 WorkOrder。
表结构:
WorkOrder
id
customer_id
create_date
...
示例数据:
WorkOrder.id WorkOrder.customer_id WorkOrder.create_date ...
1 1 2012-01-01 12:00:00
2 1 2016-06-29 12:00:00
3 2 2015-05-05 12:00:00
期望的结果:
WorkOrder.id WorkOrder.customer_id WorkOrder.create_date ...
2 1 2016-06-29 12:00:00
3 2 2015-05-05 12:00:00
当前代码:
$query = DB::table('WorkOrder')
->orderBy('WorkOrder.create_date', 'desc')
->groupBy('WorkOrder.customer_id');
// select * from `WorkOrder` group by `WorkOrder`.`customer_id` order by `WorkOrder`.`create_date` desc
当前结果:
WorkOrder.id WorkOrder.customer_id WorkOrder.create_date ...
1 1 2012-01-01 12:00:00
3 2 2015-05-05 12:00:00
最佳答案
使用最大值函数
SELECT WorkOrder.id, WorkOrder.customer_id, MAX(WorkOrder.create_date) FROM `WorkOrder` GROUP BY `WorkOrder`.`customer_id` ORDER BY `WorkOrder`.`create_date` DESC
关于mysql - 通过最大列值选择每个唯一列值限制一行，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/38106063/