Multi valued attributes in a table

Question

I have designed a send message system in which users can send a message to more than one person at a time. so the recipient attribute of a message is multi valued. so i designed an other table called message_recipients.

Here are my tables:

create table `message`(
`message_id`           INT(11)      NOT NULL primary key auto_increment,
`sender`               VARCHAR(32)  NOT NULL,
`topic`                VARCHAR(100) NOT NULL,
`content`              TEXT         NOT NULL,
`message_date`         TIMESTAMP    NOT NULL  ,
`readed`               VARCHAR(1)   NOT NULL DEFAULT 0,
`deleted_by_sender`    VARCHAR(1)   NOT NULL DEFAULT 0,
`deleted_by_recipient` VARCHAR(1)   NOT NULL DEFAULT 0,
FOREIGN KEY(sender)    REFERENCES   users(user_name)
)ENGINE=InnoDB DEFAULT CHARSET=utf8;


create table `message_recipients`(
`message_id` INT         NOT NULL ,
`recipient`  VARCHAR(32) NOT NULL ,
PRIMARY KEY(message_id,recipient),
FOREIGN KEY(message_id) REFERENCES message(message_id) on delete cascade,
FOREIGN KEY(recipient)  REFERENCES users(user_name)
)ENGINE=InnoDB default charset=utf8;

When i insert a message in message table i need to get its message_id and insert it with recipient or recipients into message_recipients table.

Here is my script:

insert into `message`(`sender`,`topic`,`content`)
values('me','need help','how to get last inserted row');
select message_id from `message` order by `message_id` desc limit 0,1;

When i got the message_id , i can now insert it into message_recipients with some users as recipient, and now question is that; is there any better or more optimized way?

Answer 1

Use the function mysql_insert_id() instead of

select message_id from `message` order by `message_id` limit 0,1;

This is a built-in MySQL method that will get you the just inserted primary key. The SELECT statement above might not be reliable if there are a large number of simultaneous inserts.