需要帮助合并三个表的外键

Question

我创建了三个这样的表，

1.

CREATE TABLE person (
id int NOT NULL AUTO_INCREMENT,
name varchar(50) NOT NULL,
age int,
PRIMARY KEY (id)
);

2.

CREATE TABLE address (
id int NOT NULL AUTO_INCREMENT,
city varchar(50) NOT NULL,
post_code int NOT NULL,
person_id int NOT NULL,
PRIMARY KEY (id),
FOREIGN KEY (person_id) REFERENCES person(id)
);

3

CREATE TABLE subjects (
id int NOT NULL AUTO_INCREMENT,
subjects_s varchar(50) NOT NULL,
address_id int NOT NULL,
PRIMARY KEY (id),
FOREIGN KEY (address_id) REFERENCES address(id)
);

现在在表格中我有一些这样的信息：

人

+----+--------+------+
| id | name   | age  |
+----+--------+------+
|  1 | Sohan  |   17 |
|  2 | Farhan |   18 |
+----+--------+------+

地址

+----+-------+-----------+-----------+
| id | city  | post_code | person_id |
+----+-------+-----------+-----------+
|  1 | Tongi |      1711 |         1 |
|  2 | Dhaka |      1230 |         2 |
+----+-------+-----------+-----------+

学科

+----+--------------------+------------+
| id | subjects_s         | address_id |
+----+--------------------+------------+
|  1 | Accounting Finance |          1 |
|  2 | Physics Math       |          2 |
+----+--------------------+------------+

现在我想把所有这些数据一起展示。我怎样才能做到这一点？请帮忙！

Answer 1

您应该能够使用 SQL join 语句来组合这些。

语法在MySQL join documentation中有详细说明。

对于您的表，您的查询应如下所示：

SELECT person.*, address.*, subjects.* 
  FROM person 
    JOIN address ON person.id = address.person_id 
    JOIN subjects ON address.id = subjects.address_id

请记住，此示例使用内部联接，根据您表中的数据，这可能不是正确的联接类型。我建议阅读上面链接的文档以获得进一步的指导。

需要帮助合并三个表的外键

Need help in merging three tables foreign keys

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