Postgres - Inserting data from another table for one column only

Question

I am attempting the following query in Postgres 9.6.3

INSERT INTO join_table ("table_1_id", "table_2_id") VALUES
      (7, SELECT "id" from "table_2" where label='Foo Bar');

This throws ERROR: syntax error at or near "SELECT" at character 94

I have seen examples for nested selects inside of an insert statement work where only the things being selected are inserted. Is the above query even possible?

Answer 1

Try putting parens around the sub-query:

INSERT INTO join_table ("table_1_id", "table_2_id") VALUES
      (7, (SELECT "id" from "table_2" where label='Foo Bar'));

Answer 2

Use insert . . . select. values is unnecessary:

INSERT INTO join_table (table_1_id, table_2_id)
    SELECT y, "id" 
    FROM "table_2" 
    WHERE label = 'Foo Bar';

This also allows you to insert multiple rows from the other table.