MySQL - How to insert into table that has many-to-

Question

I have a table of persons. Each person has a property and many persons may have a certain property. So this is a many-to-many relationship. This is the schema:

CREATE TABLE persons (
  person_id int(11) NOT NULL AUTO_INCREMENT,
  firstname varchar(30) NOT NULL,
  lastname varchar(30) NOT NULL,
  PRIMARY KEY (person_id)
);

CREATE TABLE properties (
  property_id int(11) NOT NULL AUTO_INCREMENT,
  property varchar(254) NOT NULL UNIQUE,
  PRIMARY KEY (property_id)
);

CREATE TABLE has_property (
  person_id int(11) NOT NULL,
  property_id int(11) NOT NULL,
  PRIMARY KEY (person_id,property_id),
  FOREIGN KEY (person_id) REFERENCES persons (person_id),
  FOREIGN KEY (property_id) REFERENCES properties (property_id)
);

Now lets say i want to insert to the database this person:

• firstname:'John'
• lastname:'Doe'
• properties:'property_A','property_B','property_C'

persons

+-----------+-----------+----------+
| person_id | firstname | lastname |
+-----------+-----------+----------+
|         1 | John      | Doe      |
+-----------+-----------+----------+

properties

+-------------+------------+
| property_id |  property  |
+-------------+------------+
|           1 | property_A |
|           2 | property_B |
|           3 | property_C |
+-------------+------------+

has_property

+-----------+-------------+
| person_id | property_id |
+-----------+-------------+
|         1 |           1 |
|         1 |           2 |
|         1 |           3 |
+-----------+-------------+

So far the best thing i have thought is to do a regular insert in the persons table:

INSERT INTO persons (firstname,lastname) VALUES ('John','Doe');

and then do a select to find the id of the person i just inserted

SELECT person_id FROM persons WHERE firstname='John' AND lastname='Doe';

in order to insert into the other two tables (because i need to know the person_id). But i think there must be a better way, isn't it?

Answer 1

Here is what i ended up doing. I hope it helps someone.

INSERT INTO persons (firstname,lastname) VALUES ('John','Doe');
SET @person_id = LAST_INSERT_ID();

INSERT IGNORE INTO properties (property) VALUES ('property_A');
SET @property_id = LAST_INSERT_ID();
INSERT INTO has_property (person_id,property_id) VALUES(@person_id, @property_id);

INSERT IGNORE INTO properties (property) VALUES ('property_B');
SET @property_id = LAST_INSERT_ID();
INSERT INTO has_property (person_id,property_id) VALUES(@person_id, @property_id);

INSERT IGNORE INTO properties (property) VALUES ('property_C');
SET @property_id = LAST_INSERT_ID();
INSERT INTO has_property (person_id,property_id) VALUES(@person_id, @property_id);