MySQL - how to lock a single row? - mysql

Question

My aim is to create a system to book trips. My system is built in MySQL + PHP. I'm using InnoDB as engine in MySQL.
When an user choose which trip he wants to book, I want the ipothetic page "*.php" to lock one of those trip for some times (ex. 10 minutes) and after this time release it.
Which is the best way to lock the trip in the DB?
Notice that I didn't talk about rows or table because I'm asking for the easiest way to implement this kind of feature and I'm not sure if mines is that one. So I've tried to design a table to contain the trips, and look like this:
CREATE TABLE IF NOT EXISTS Trip (
id INT(1) NOT NULL AUTO_INCREMENT,
descr VARCHAR(50) NOT NULL,
quantity INT(2) NOT NULL DEFAULT 10,
PRIMARY KEY (id)
) Engine=InnoDB

Answer 1

This is your Ticket table
CREATE TABLE IF NOT EXISTS Trip (
id INT(1) NOT NULL AUTO_INCREMENT,
descr VARCHAR(50) NOT NULL,
quantity INT(2) NOT NULL DEFAULT 10,
PRIMARY KEY (id)
) Engine=InnoDB
Let me visualize your user table as this ( just for testing )
CREATE TABLE IF NOT EXISTS `user` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`name` text COLLATE utf8mb4_unicode_ci NOT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci AUTO_INCREMENT=1 ;
Now You need add an extra table where you can track your users booking order ( Example like this )
CREATE TABLE IF NOT EXISTS `trip_track` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`user_id` int(11) NOT NULL,
`trip_id` int(11) NOT NULL,
`timestamp` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci AUTO_INCREMENT=1 ;
Now Every time you insert a booking query you need to insert user_id,ticket_id and timestamp ( You can use date or Mysql's default time stamp )
Then whenever user tries to book any ticket use a Query to check the time difference between current time and the timestamp from the database
That's it! .. see? that's simple :)