DISTINCT 或 GROUP BY 不适用于 return 个唯一值

Question

SELECT DISTINCT order_reference as barcode,
    mth.location as location,
    mth.last_update_ts as updated
FROM sales_order_header soh
INNER JOIN manufacturing_tracking_history mth
    ON soh.id = mth.sales_order_header_id
GROUP BY barcode, location, updated
ORDER BY updated DESC
LIMIT 3000;

     barcode                           location             updated
0     BR2MGK    Tracking.Tracking.Tracking.TT03 2020-09-16 17:18:02
1     BR2MGK    Surfacing.Blocking.Blocking.AB8 2020-09-16 17:25:53
2     BR2MGK    Surfacing.Blocking.Blocking.AB8 2020-09-16 17:27:43
3     BR2MGK     Surfacing.Blocking.Blocking.C6 2020-09-16 17:37:23
4     BR2MGK    Tracking.Tracking.Tracking.BKCT 2020-09-16 17:41:13

我只需要每个条形码的最新更新位置，但我无法实现。请帮助我是新手

Answer 1

我认为您可以像这样使用 Row_number() 来做到这一点：

select barcode, location, updated from (
SELECT order_reference as barcode,
    mth.location as location,
    mth.last_update_ts as updated,
row_number() over(partition by order_reference order by mth.last_update_ts desc) rw
FROM sales_order_header soh
INNER JOIN manufacturing_tracking_history mth
    ON soh.id = mth.sales_order_header_id
) t
where t.rw=1
limit 3000;

DISTINCT 或 GROUP BY 不适用于 return 个唯一值

DISTINCT nor GROUP BY doesn't work to return unique values

sql

greatest-n-per-group