从mysql自动增量主键分配外键

Question

mysql新手，感谢任何帮助。

我有三个表格：organizations，locations和shows。我想使用organizations和locations的自动增量分配主键作为shows中的外键。当我为该表输入值时，代码mysql如何自动为shows拉外键？或者，当我在shows中输入每行的值时，根据自动递增的主键自动分配的值，手动分配是最佳做法吗？

下面是我创建的所有三个表，都organizations和locations已插入所有条目（并通过自动增量分配因而主键）：

组织

CREATE TABLE organizations(
    id MEDIUMINT NOT NULL AUTO_INCREMENT, 
    name VARCHAR(64) NOT NULL, 
    sex CHAR(1) NOT NULL, 
    start_year YEAR NOT NULL, 
    end_year YEAR NOT NULL, 
    notes LONGTEXT, 
    PRIMARY KEY (id) 
    ); 

地点

CREATE TABLE locations (
    id MEDIUMINT NOT NULL AUTO_INCREMENT, 
    name VARCHAR(64) NOT NULL, 
    address_name VARCHAR(64) NOT NULL, 
    address_lat FLOAT(10,6) NOT NULL, 
    address_long FLOAT(10,6) NOT NULL, 
    type VARCHAR(64) NOT NULL, 
    notes LONGTEXT, 
    PRIMARY KEY (id) 
    ); 

个

显示

CREATE TABLE shows (
    id MEDIUMINT NOT NULL AUTO_INCREMENT, 
    organization_id MEDIUMINT NOT NULL, 
    location_id MEDIUMINT NOT NULL, 
    date DATE NOT NULL, 
    cost DECIMAL (2,2), 
    money_raised DECIMAL (6,2), 
    charity VARCHAR(64), 
    audience_size MEDIUMINT, 
    band VARCHAR(64), 
    blackface CHAR(1), 
    drag CHAR(1), 
    notes LONGTEXT, 
    PRIMARY KEY (id) 
    ); 


ALTER TABLE shows 
    ADD CONSTRAINT FK1_shows 
    FOREIGN KEY (organization_id) REFERENCES organizations(id) 
    ON UPDATE CASCADE 
    ON DELETE CASCADE; 

ALTER TABLE shows 
    ADD CONSTRAINT FK2_shows 
    FOREIGN KEY (location_id) REFERENCES organizations(id) 
    ON UPDATE CASCADE 
    ON DELETE CASCADE; 

Answer 1

你可以使用它选择ID基于name值的其它表值，像这样的插入语句：

INSERT INTO shows (
    organization_id, 
    location_id, 
    date 
) VALUES (
    (SELECT id FROM organizations WHERE name = 'my_org_name'), 
    (SELECT id FROM locations WHERE name = 'my_loc_name'), 
    '2016-05-01' 
); 

当然，你会插入一些其他列的值。