Insert into … values ( SELECT … FROM … ) in postgresql?

Question

I am working with Postgresql database. I have one database which is - db1 and I have one table inside this database which is App1.

I need to make a select query against this App1 table which is in db1 and then whatever results I am getting back, I need to insert them in App2 table as it is which is in another database db2.

Below is my query which I am running against App1 table which is in db1 -

select col1, col2 from App1 limit 5

Now is there any way I can use Insert statement along with above SELECT statement which can insert into App2 table for me automatically which is in db2?

Something along this line -

Insert into … values ( SELECT … FROM … )

Is this possible to do in Postgresql as both the tables are in different database?

Answer 1

To do this between databases you must use the foreign data wrapper postgres_fdw or use dblink. See the documentation. PostgreSQL doesn't support cross-database SELECT.

Often, if you find yourself wanting to do this, you should be using separate schemas in a single database instead.

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BTW, it's generally:

INSERT INTO ... SELECT ...

i.e. there's no subquery, no parentheses. That's because the VALUES clause is actually a standalone statement too:

INSERT INTO ... VALUES ...

observe:

regress=> VALUES (1,2), (2,3);
 column1 | column2 
---------+---------
       1 |       2
       2 |       3
(2 rows)