postgresql - 将列值从一个表更新到另一个表

Question

我有三个表

X [id,event_time]
Y [x_id,z_id] -- here x_id is id from X and z_id is id from Z
Z [id,event_time]

现在我想用 Z[event_time] 更新 X[event_time] 的值。是否可以为此形成任何查询？

Answer 1

update x
set x.event_time = t.event_time
from (
    select z.event_time
        ,y.x_id
    from z
    join y on z.id = y.z_id
    ) t
where x.id = t.x_id