將數據插入到postgres中的相關表中

Question

我想在一個語句中插入一個對象（跨越一個主表和兩個相關表）的所有數據（如果可能的話）。如果我只有一個相關的表，我想我可以做這樣的事情使用公用表表達式：

WITH foo AS (INSERT INTO foos VALUES (....) RETURNING id) 
INSERT INTO bar VALUES (foo.id....) 

難道我能夠做這樣的事，但對於一個以上的相關表？

Answer 1

您可以根據需要將您的格式擴展到多個表格。這裏是一個主表和兩個相關表格，並取回最終結果的幾種方法的例子：

這些都是使用的表：

CREATE TABLE main 
(
    main_id serial PRIMARY KEY, 
    main_text text 
) ; 
CREATE TABLE age 
(
    main_id integer REFERENCES main(main_id) PRIMARY KEY, 
    birthdate date NOT NULL, 
    CHECK(birthdate <= now()) 
) ; 
CREATE TABLE preferred_colours 
(
    main_id integer NOT NULL REFERENCES main(main_id), 
    colour text NOT NULL, 
    PRIMARY KEY(main_id, colour) 
) ; 

這是一個CTE，你在三個表中插入，並取得了一些成果：

WITH insert_main AS 
(
    INSERT INTO main (main_text) 
    VALUES ('Main text') 
    RETURNING main_text, main_id 
) 
, insert_age AS 
(
    INSERT INTO age (main_id, birthdate) 
    VALUES ((SELECT main_id FROM insert_main), '2017-01-01') 
    RETURNING main_id, birthdate 
) 
, insert_colours AS 
(
    INSERT INTO preferred_colours (main_id, colour) 
    SELECT 
     main_id, colour 
    FROM 
     insert_main 
     CROSS JOIN 
     (SELECT 'blue' AS colour 
      UNION 
      SELECT 'red' 
      UNION 
      SELECT 'green' 
     ) AS colours 
    RETURNING 
     * 
) 
SELECT 
     insert_main.main_id 
    ,insert_main.main_text 
    ,insert_age.birthdate 
    ,(SELECT string_agg(colour, ', ' ORDER BY colour) 
     FROM insert_colours 
    ) AS preferred_colours_list 
FROM 
    insert_main 
    CROSS JOIN insert_age 

 
main_id | main_text | birthdate | preferred_colours_list 
------: | :-------- | :--------- | :--------------------- 
     1 | Main text | 2017-01-01 | blue, green, red
 

dbfiddle here