postgresql: INSERT INTO … (SELECT * …)

问题

I'm not sure if its standard SQL:

 INSERT INTO tblA 
 (SELECT id, time 
    FROM tblB 
   WHERE time > 1000)

What I'm looking for is: what if tblA and tblB are in different DB Servers.

Does PostgreSql gives any utility or has any functionality that will help to use INSERT query with PGresult struct

I mean SELECT id, time FROM tblB ... will return a PGresult* on using PQexec. Is it possible to use this struct in another PQexec to execute an INSERT command.

EDIT:
If not possible then I would go for extracting the values from PQresult* and create a multiple INSERT statement syntax like:

INSERT INTO films (code, title, did, date_prod, kind) VALUES
    ('B6717', 'Tampopo', 110, '1985-02-10', 'Comedy'),
    ('HG120', 'The Dinner Game', 140, DEFAULT, 'Comedy');

Is it possible to create a prepared statement out of this!! :(

回答1:

As Henrik wrote you can use dblink to connect remote database and fetch result. For example:

psql dbtest
CREATE TABLE tblB (id serial, time integer);
INSERT INTO tblB (time) VALUES (5000), (2000);

psql postgres
CREATE TABLE tblA (id serial, time integer);

INSERT INTO tblA
    SELECT id, time 
    FROM dblink('dbname=dbtest', 'SELECT id, time FROM tblB')
    AS t(id integer, time integer)
    WHERE time > 1000;

TABLE tblA;
 id | time 
----+------
  1 | 5000
  2 | 2000
(2 rows)

PostgreSQL has record pseudo-type (only for function's argument or result type), which allows you query data from another (unknown) table.

Edit:

You can make it as prepared statement if you want and it works as well:

PREPARE migrate_data (integer) AS
INSERT INTO tblA
    SELECT id, time
    FROM dblink('dbname=dbtest', 'SELECT id, time FROM tblB')
    AS t(id integer, time integer)
    WHERE time > $1;

EXECUTE migrate_data(1000);
-- DEALLOCATE migrate_data;

Edit (yeah, another):

I just saw your revised question (closed as duplicate, or just very similar to this).

If my understanding is correct (postgres has tbla and dbtest has tblb and you want remote insert with local select, not remote select with local insert as above):

psql dbtest

SELECT dblink_exec
(
    'dbname=postgres',
    'INSERT INTO tbla
        SELECT id, time
        FROM dblink
        (
            ''dbname=dbtest'',
            ''SELECT id, time FROM tblb''
        )
        AS t(id integer, time integer)
        WHERE time > 1000;'
);

I don't like that nested dblink, but AFAIK I can't reference to tblB in dblink_exec body. Use LIMIT to specify top 20 rows, but I think you need to sort them using ORDER BY clause first.

回答2:

If you want insert into specify column:

INSERT INTO table (time)
(SELECT time FROM 
    dblink('dbname=dbtest', 'SELECT time FROM tblB') AS t(time integer) 
    WHERE time > 1000
);

回答3:

You can use dblink to create a view that is resolved in another database. This database may be on another server.

回答4:

This notation (first seen here) looks useful too:

insert into postagem (
  resumopostagem,
  textopostagem,
  dtliberacaopostagem,
  idmediaimgpostagem,
  idcatolico,
  idminisermao,
  idtipopostagem
) select
  resumominisermao,
  textominisermao,
  diaminisermao,
  idmediaimgminisermao,
  idcatolico ,
  idminisermao,
  1
from
  minisermao

回答5:

Here's an alternate solution, without using dblink.

Suppose B represents the source database and A represents the target database: Then,

Copy table from source DB to target DB:

pg_dump -t <source_table> <source_db> | psql <target_db>

Open psql prompt, connect to target_db, and use a simple insert:

psql
# \c <target_db>;
# INSERT INTO <target_table>(id, x, y) SELECT id, x, y FROM <source_table>;

At the end, delete the copy of source_table that you created in target_table.
```
# DROP TABLE <source_table>;
```

回答6:

insert into TABLENAMEA (A,B,C,D) 
select A::integer,B,C,D from TABLENAMEB

来源：https://stackoverflow.com/questions/6083132/postgresql-insert-into-select

标签

sql

postgresql

insert

dblink