如何从查询与数据列表中联接数据？

Question

Two tables with some data in the second one.

CREATE TABLE IF NOT EXISTS dst (
  id integer NOT NULL,
  content varchar(200) NOT NULL);

CREATE TABLE IF NOT EXISTS src (
  id integer NOT NULL,
  name varchar(200) NOT NULL);

INSERT INTO src VALUES('100', 'ET'), ('200', 'Luke'), ('300', 'Jojo');

Now, I insert one selected id from src and some other list of values. So the result should look like this:

200, one
200, two
200, three

And this is my try of

INSERT INTO dst (id, content) 
SELECT * FROM ((SELECT id FROM src WHERE name = 'Luke') AS bar 
CROSS JOIN ('one', 'two', 'three')) AS foo;

The issue is how can I put the second argument for JOIN - ('one', 'two', 'three'), because this way doesn't work. ERROR: syntax error at or near "'one'"

Answer 1

Use UNION ALL (in your case you didn't alias the column of the second subquery. eg as content , and comma seperated strings ('one','two','three') will not work, should be converted to a query )

INSERT INTO dst (id, content) 
 SELECT bar.id, foo.content 
   FROM
   (
    ( SELECT id FROM src WHERE name = 'Luke' ) as bar
    CROSS JOIN 
    (
     SELECT 'one' as content UNION ALL
     SELECT 'two' UNION ALL
     SELECT 'three'
    ) as foo
   )

Answer 2

An alternative solution is to use unnest() - this will convert an array into rows:

select
    unnest(array['one', 'two', 'three']::varchar[]) as content

Would yield

content (varchar)
---------------
one
two
three

This is implicitly cross joined when used in a select statement:

insert into dst (
    id,
    content
) (
    select
        src.id,
        unnest(array['one', 'two', 'three']::varchar[])
    from
        src
    where
        src.name = 'Luke'
);