如何使用select查询的输出作为insert查询的输入? [英] How to use the output of select query as an input in the insert query?

问题描述

我有以下两个表:-

postgres=# select * from district;
 id |   name
----+-----------
  1 | Ahmedabad
  2 | Barmer
(2 rows)

postgres=# select * from warehouse;
 id | name | district_id
----+------+-------------
(0 rows)

我指的是仓库的区表.现在我想插入到仓库中.我正在使用以下查询

I am referring district table from warehouse. Now I want to insert into warehouse. I am using following query

postgres=# insert into warehouse
(name, district_id)
values
('Ghodasar-WH', select id from district where name = 'Ahmedabad');
ERROR:  syntax error at or near "select"
LINE 4: ('Ghodasar-WH', select id from district where name = 'Ahmeda...

但它给了我错误，如上所示.为什么我不能在插入查询中使用另一个选择查询的结果，就像我在上面的查询中所做的那样?我认为，我正在做的是一个有效的场景.是否有任何限制，使其无法成为有效案例?

But it gives me error, as shown above. Why I can't use the result of another select query in the insert query, as I am doing in above query ? I think, what I am doing is a valid scenario. Is there any limitations, that's preventing it from a valid case ?

提前致谢.

推荐答案

Vao Tsun 有使用 insert 的正确答案...选择(并适当投票).

Vao Tsun has the correct answer for using insert . . . select (and duly upvoted).

但是，您正在尝试在 values() 中使用子查询.这是允许的，但子查询需要它自己的括号.所以你的版本可以作为:

However, you are trying to use a subquery in values(). That is allowed, but a subquery needs its own parentheses. So your version would work as:

insert into warehouse (name, district_id)
    values ( 'Ghodasar-WH', (select id from district where name = 'Ahmedabad') );

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