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[英]MySQL - Constraint to Force New Record Field Value to be Greater than Previous Record Field Value
[英]Updating field by previous record field value
我想从同一表中的先前记录日期字段更新日期字段,例如:
ID_1 ID_2 start_date end_date
1 33 2017-12-14 10:28:32.203000 null
1 33 2017-12-13 10:28:29.153000 null
1 33 2017-12-12 10:28:25.246000 null
1 33 2017-12-11 10:28:21.917000 null
2 4 2017-12-10 10:28:18.005000 null
2 4 2017-12-09 10:28:14.145000 null
2 4 2017-12-08 13:24:26.964834 null
我想通过具有相同ID_1和ID_2的Recod中的前一个start_date值来更新end_date字段。 举个例子 :
ID_1 ID_2 start_date end_date
2 4 2017-12-08 13:24:26.964834 2017-12-09 10:28:14.145000
谢谢
在Postgres中,您可以执行以下操作:
update t
set end_date = tn.next_start_date
from (select t.*,
lead(start_date) over (partition by id_1, id_2 order by start_date) as next_start_date
from t
) tn
where tn.id_1 = t.id_1 and tn.id_2 = t.id_2 and tn.start_date = t.start_date
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