如何在 postgres 的条件插入中使用插入值

Question

insert into addresses(street, city, user_id)
select 
      'street1','LA', 2
where exists (select * from users where users.id = $$$$$ AND users.storeaddress='true'))

仅当用户的 storeaddress 值为“true”时，我才想插入用户的地址。

我希望 sql 自动使用 2 代替 $$$$$。如何在sql中做到这一点？

如果我简单地用 user_id 代替 $$$$$ 我得到

HINT:  There is a column named "user_id" in table "addresses", but it cannot be referenced from this part of the query.

Answer 1

您可以使用 CTE 来提供值：

with data (street, city, user_id) as (
  values ('street1','LA', 2)
)
insert into addresses(street, city, user_id)
select *
from data
where exists (select * 
              from users
              where users.id = data.user_id 
                and users.storeaddress = true);

或者派生表：

insert into addresses(street, city, user_id)
select *
from (
   values ('street1','LA', 2)
) as data (street, city, user_id)
where exists (select * 
              from users
              where users.id = data.user_id 
                and users.storeaddress = true);