MySQL的加入爲相同的值上插入

Question

鑑於這些表：

create table country 
(
    country_id integer  primary key auto_increment, 
    name  varchar(16) unique not null 
); 
insert into country(name) values 
    ('USA'), 
    ('Canada'); 

create table network 
(
    network_id integer primary key auto_increment, 
    name  varchar(32) not null, 
    country_id integer references country(country_id) 
     on cascade update 
     on delete restrict 
); 

我想執行的insert into network(country_id, name) values，其中name是值的列表，但country_id爲每個行相同，一個子查詢的結果像select country_id from country where name = 'Canada'。我想在一個插入中完成所有操作，而不是之後更新的插入。我認爲它要求join，但我不確定。

想法？

Answer 1

INSERT INTO network 
    (country_id, name) 
SELECT 
    c.country_id, n.network_name 
FROM 
    (SELECT country_id 
     FROM country 
     WHERE name = 'Canada' 
    ) AS c 
    CROSS JOIN 
    (SELECT 'name1' AS network_name UNION ALL 
     SELECT 'name2' UNION ALL 
     SELECT 'name3' UNION ALL 
     ... 
     SELECT 'nameN' 
    ) AS n ; 

---

的Sidekick：不要不在MySQL內聯定義外鍵，它們是忽略：

create table network 
(
    network_id integer primary key auto_increment,  --- PK fine, not ignored 
    name  varchar(32) not null, 
    country_id integer references country(country_id) --- this FK is ignored 
     on cascade update 
     on delete restrict 
); 

定義他們列清單後，分別。我更喜歡在列後面定義主鍵約束：

CREATE TABLE network 
(
    network_id INTEGER  NOT NULL AUTO_INCREMENT, 
    name  VARCHAR(32) NOT NULL, 
    country_id INTEGER  NULL, 

    PRIMARY KEY (network_id), 

    FOREIGN KEY (country_id)    --- FK not ignored 
     REFERENCES country (country_id) 
     ON CASCADE UPDATE 
     ON DELETE RESTRICT 
);